Age Before Duty : THE MACGUFFIN <i> By Stanley Elkin</i> , <i> (Linden Press: $19.95; 320 pp.) </i>

Muttering, expostulating, wisecracking and scheming against the real or imaginary schemes against him, Bobbo Druff is 58, going downhill, and living--this municipal politician of only average scope and only average honesty--a life of noisy desperation.

Bobbo, with the limousine he gets as commissioner of streets, the made-to-order suits, the regular lunch table among the City Hall crowd and the stuffed envelopes he never solicits but which visitors leave on his desk anyway; this Bobbo is Stanley Elkin’s Everyman. Everyman lapped by approaching old age, Everyman slipping.

His mind is not slowing down; if anything, it is speeding up. Yet he seems to be losing force, edge. His head is filled with “chirps and squeaks and other freezing noises.” Acquaintances remind him of things he did when he was younger; his subordinates are deferential and suspiciously officious.

To grow old is to see less, hear less; to feel you are falling out of touch, to feel you are losing control. With peripheral vision clogging up, is the man ahead holding the door for you or trying to close it against you? Bobbo wonders.

Dick, his driver, mentions a municipal retraining program; will Bobbo lose his car? When he goes for a fitting, the tailor seems momentarily inattentive; is word out that he is on the way out? There is worse. His suit is measured correctly, yet he looks terrible in it. Is his body also preparing to ditch him?

“It was at least past middle age in his head and even later than that in the cut of his cloth, his chest caving behind his shirts, emptying out at his torso, sinking, lowering into trousers rising like a tide and lapping about him in waves,” Elkin writes. “The suit fit Druff, Druff just didn’t fit the suit.”

“The MacGuffin” is Elkin’s gnarled, comic, baroque account of how, for 36 hours or so, Bobbo Druff embarks upon a picaresque series of sorties against the fading of the light. He flaps and dazzles in the net closing around him; it only draws the net tighter; he ends up half-domesticated, half-unappeased.

In Alfred Hitchcock’s films, a macguffin is a device more or less external to the action that sets the action going. (It would have been nice if Elkin, a cantankerous and gifted writer, had provided a note for Hitchcock non-devotees; perhaps he wants to screen them out.) To get his action going, to battle nets, Druff engages in some improbable extravagances.

Long married and faithful to Rose Helen, his college sweetheart, and with a grown son living at home, Druff approaches Meg at the bar of his lunchtime hangout. She is 50-ish, attractive, a department-store buyer, and not at all backward; still, he astounds her by hustling her into his limousine and insisting that she become his mistress.

“No, of course not,” she declares. “I don’t know you. You’re old, you’re crazy, you’re married, you’re not a sharp dresser.” Druff argues, outrageously, that he is perfect for her. Being married and a public figure, he is an ideal subject for extortion, should the need arise.

Meg, no extorter, is secretly tickled. Druff knows he has made a fool of himself but the important thing is that he has acted with strength. And when he phones her later, she agrees to have dinner that night. They go to her apartment afterwards, and one thing leads to another. Druff is delighted that it still can.

He is on a high, but of the most disastrous kind. Druff has rebelled against his aging condition, but he is his aging condition. He is too old to step outside himself; instead of challenges, as they might be to a younger man, normal complications become sinister threats. Druff’s sparks of incipient paranoia blaze into conflagration.

“The MacGuffin” has Druff wandering about the city--an unnamed place in the Middle West--for two days and a night, mostly in his limousine but sometimes by taxi, or hitchhiking. He is in a kind of fugue state, though he specifically denies it. As he talks--to Dick, his driver; to Meg; to Rose Helen; to Mike, his son, and mostly to himself--the problems and tensions of his life take on distorting-mirror shapes.

Dick, he is sure, is spying on him; so is Doug, the relief driver. The limousine is bugged. Everything that he notices, everyone he talks to, shows signs of being part of a vast conspiracy. The central figures, he is certain, are a former girlfriend of Mike’s, an Arab student who is run over and killed at a pedestrian crossing beside the university; and the university lawyer who comes to talk to him about building an overpass.

Just what the conspiracy is, he is not sure, but it has something to do with Oriental rugs. He notices such a rug in the limousine used by the mayor, his political rival; in Meg’s apartment; in the study of a local rabbi. His feverish pursuit of clues is another macguffin. Like his night with Meg, it is a passion to stave off decline; and it too unravels. At the end, Druff is at home, eating Rose Helen’s warmed-up turkey and trying vainly to explain what he has been up to. He is exhausted, safe, unregenerate and old.

Druff’s cogitations and flights are feverish and unstoppable. There is a charm to the man; he can be sharply lucid and very funny. Elkin roots him solidly, despite his wanderings, in his uneasy municipal role. He is full of notions about reform, for example. He imagines proposing a new federal constitution that deals with the things that really matter to people, such as bank-statement errors and rules for warranties. At the same time, he is a stolid and down-to-earth hack.

Most of the other characters are simply flames in Druff’s mental bonfire. Rose Helen, his wife, stands in her own right, but a long section dealing with their youthful courtship doesn’t fit in very well. More persuasive are the sections dealing with Mike, Druff’s overgrown, needy son whose anguish feeds Druff’s own, and with whom, at the end, he is tentatively reconciled.

Elkin’s style is as feverish as Druff’s. He uses a whorled impasto, like a desperate Van Gogh. One senses an anguish linking the author--who in his best works, such as “The Magic Kingdom,” writes at his own perilous edge--and his character.

Too often the texture is so thick as to bury its own virtues. It is a hedge of brambles with a number of overstressed roses. Roses, nevertheless.