Angry about mixed styles of music (9)
I believe the answer is:
crossover
'mixed styles of music' is the definition.
(crossover genre)
'angry about' is the wordplay.
'angry' becomes 'cross' (cross can mean annoyed or angry).
'about' becomes 'over' (both can mean around).
'cross'+'over'='CROSSOVER'
(Other definitions for crossover that I've seen before include "Rock opera perhaps" , "Point of intersection" , "affecting different functions" , "in a mixture of styles" , "combining distinct styles" .)