What hip-hop artist does, turning up for fight (4)
I believe the answer is:
spar
'for fight' is the definition.
(sparring is a kind of fighting)
'what hip-hop artist does turning up' is the wordplay.
'what hip-hop artist does' becomes 'raps'.
'turning up' says the letters should be written in reverse.
'raps' in reverse letter order is 'SPAR'.
(Other definitions for spar that I've seen before include "Pole used in boat etc - box" , "Length of wood" , "Translucent mineral" , "Box; various minerals" , "Shadow-box" .)