Do some crude painting (4)
I believe the answer is:
daub
'do some crude painting' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for daub that I've seen before include "Do graffiti" , "Coat with plaster" , "Smear; plaster" , "Crude painting" , "Smear; bad painting" .)