Painter's fag ends picked up (6)
I believe the answer is:
stubbs
'painter's' is the definition.
(painter George Stubbs)
'fag ends picked up' is the wordplay.
'fag ends' becomes 'stubs' (ends of a cigarette).
'picked up' shows a homophone (sound like).
'stubs' is a homophone of 'STUBBS'.
(Other definitions for stubbs that I've seen before include "English painter" , "Horse painter, d. 1806" , "English artist" , "Artistic horseman" , "George --, painter known for horse portraits" .)