There's a hint of back-alley cool about Slates Supperclub, a Walnut Creek dinner house and jazz boite on a block-long back street near Civic Drive. The sign is small, and the entrance, a narrow door in a rusty facade, harks back to a 1920s speakeasy. When you brush through the long velvet drapes of this former Chinese restaurant, it's apparent that the owners have made music an integral part of the ambience. A cubbyhole lined with burgundy velvet cozily accommodates the evening's duet or trio. Tables covered in white provide seating up front, while higher bare-top tables offer a good line of sight down the long, narrow space. Up a few steps from the dark and noisy slate floor, cocktail tables allow patrons to keep an eye on the action. Even the bar, at the rear of the club, preserves the view. Paintings of jazz club scenes make the room feel hip and cool. Slates, open since November, is an ambitious pairing of live jazz and food with aspirations. Previous experience with such combinations had left me dubious: There may be stellar jazz, but the food can be inedible. But there are clearly experienced hands at work in Slates' kitchen, even when a dish is less than perfect.