Coarsely humorous (6)
I believe the answer is:
ribald
'coarsely humorous' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for ribald that I've seen before include "Humourous in vulgar way" , "Funny, but not nice" , "Humorously vulgar" , "Obscene" , "Coarsely mocking" .)