Sharp rap but different (6)
I believe the answer is:
abrupt
'sharp' is the definition.
(I know that sharp can be written as abrupt)
'rap but different' is the wordplay.
'different' indicates anagramming the letters.
'rap'+'but'='rapbut'
'rapbut' anagrammed gives 'ABRUPT'.
(Other definitions for abrupt that I've seen before include "Curt and brief" , "Sudden - blunt" , "Short and brusque" , "Rough and quick" , "Curt; precipitous" .)