William Clarke, Thursday, January 19, at Herman's Hideaway, is a California native and harmonicat who caught the blues bug at sixteen. While his peers were listening to Beach Boys tunes, Clarke was sneaking into Watts dives in order to learn at the feet of Lowell Fulsom and Big Mama Thornton. Later, while eking out a living as a machinist, he became a pupil of ex-Muddy Waters sideman George "Harmonica" Smith, a player who helped define the harp as one of the Chicago sound's most important instrumental voices. Finally, in the late Eighties, Clarke took up the blues torch full-time, and he is now celebrating the release of Groove Time, his third recording for Alligator Records. The disc finds him surveying Chicago, West Coast and Deep South subgenres (he offers fine covers of tunes by Sleepy John Estes and Arthur "Big Boy" Crudup) and displays his impressive compositional skills. And when Clarke's not blowing, he's got a lean, lowdown vocal style that does his tutors proud.