Clara, cool, deliberate, articulate, is a sister under the (impervious) skin of Margaret Drabble's other heroines; while intellectually emancipated, she's totally ignorant particularly in social and sexual spheres. All of it explained, if not overexplained (the exposition in this new novel takes up more than half its length and the action is skeletal) by the fact that Clara comes from an economically and emotionally penurious home--in Yorkshire. Up to London on a grant, the city is indeed Jerusalem the Golden--poetry readings, experimental theatre, nonrepresentative art, and finally Clelia, lovely and clever and ""undismaying"" and her brother Gilbert, even more beautiful. Gilbert is a refugee from a disastrous marriage and he completes her initiation by taking her to Paris. Clara's summons home to her mother's bedside (she is dying of cancer) only briefly returns her to the world she is determined to escape--she does not stay for the long deathwatch....Miss Drabble, in casting a cold eye on the world she knows so well, has forgotten to make a balancing bid for the reader's sympathy. She's such an able writer it must have been an oversight.