The sentimental, romanticized saga of three generations of bird-named Clays from Sixkiller Gap in the North Carolina mountains: grandfather Bluejay Clay, Country & Western singer of the Forties; his Nashville-promoter son, Jaybird; and finally grandson Robin, a Harvard Med grad who returns to the North Carolina hills to be a doctor among kith and kin. Bluejay, with his lndian pal Sam Sixkiller, is the most stalwart of the Clays: his first hit is ""The Longer You're Gone, The Harder It Gets""--written, Bluejay claims, with no double-entendre intended (scandalized Baptists protest nonetheless); the death of a beloved wife brings on a long silence--but there's ultimately a late, triumphant return to performing at the Opry. Son Jaybird never quite makes it, however: after a bad marriage, worse divorce, drinking, and sharp practices in Nashville, he's somewhat redeemed through a lucky marriage to an aging, kind singer. So it's up to grandson Robin to re-fight the Clay reputation once again. Journalist-novelist Hemphill (The Nashville Sound, Long Gone) offers a fair capsule-history of music in Nashville as he fills out an insubstantial novel with fact-filled digressions. As fiction, however, this is too often delivered in flat journalese--while the characterizations and vignette-plotting never rise above a predictable, soggy TV-movie level.