Bongo-playing 1950s stereotype (7)
I believe the answer is:
beatnik
(Other definitions for beatnik that I've seen before include "50s hippie" , "1950s dropout" , "Young nonconformist of the 1950s and 1960s" , "Social rebel of the 1950s" , "Young person of the 1950s, nonconformist in dress and behaviour" .)