RESCUING CLAIRE by Thomas Johnson (Scarborough House: $19.95; 250 pp . ). We tend to forget how icky that transition is from the last year of our cocoon college years into the--ugh!--"real world." Love affairs become jumbled--did they actually happen or were they imagined? Pity befuddled Henry Fitzgerald, an otherwise bright young man on the Madison, Wis., campus, who is having major problems getting his life back on track, particularly as it regards the lovely Claire. Do they love each other, or did they ever? Are her woes necessarily his woes? Is he obligated to "rescue" her? From what? Why him? Thomas Johnson has a nice touch with his sometimes bumbling characters--alternately funny, sometime exasperating and frequently touching. The Midwest setting is refreshing, and Henry's scrabbling for reality will bring back sometimes painful college memories for many of us.