Criticises what hip-hop artist does (4)
I believe the answer is:
raps
This clue is a double definition.
'criticises' is the first definition.
(I've seen this in another clue)
'what hip-hop artist does' is the second definition.
(Other definitions for raps that I've seen before include "Sprechgesang pop hits" , "'Knocks, on the door say (4)'" , "Knocks sharply" , "Cracks" .)