1: A favourite car of Seattle natives. (11)
3: Burdened young man with couple of encumbrances (5)
4: Vulgar and insipid (9)
5: Go up cedar's first branch (5)
6: Crank up front half of outhouse in Alabama, for example (4-5)
7: Man, what an avant-garde US artist! (3)
9: Any environment for car maintenance (7)
12: Healers swear by the cases of the little river horse. (11)
14: Recorder describes Mr. Quayle: a little crazy person, quick on his feet (3-6)
15: Batman novel is pure horse ... ! (9)
16: Law, say, constraining trade union leaders (7)
20: Beat writer's collaborator briefly drank (5)
22: Odd bits of Niacin and Sprite (5)
24: Sixpence for big cheese? (1.1.1.)