Muddy Waters's genre (5)
I believe the answer is:
blues
'muddy waters's genre' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for blues that I've seen before include "Sort of music" , "State of depression" , "Melancholic music of black American folk origin" , "colours" , "Jazz classic (2,5,5) - See 9" .)