A composer from Harlem? (6)
I believe the answer is:
mahler
'a composer' is the definition.
(Gustav Mahler)
'from harlem?' is the wordplay.
'from' is an anagram indicator (from the letters).
'harlem' is an anagram of 'MAHLER'.
(Other definitions for mahler that I've seen before include "Vienna and New York opera conductor" , "Interrupt; hang" , "Gustav . . . . . ., Austrian composer" , "Lift" , "Austrian composer from Harlem?" .)