Dealers first to back green artist (5)
I believe the answer is:
degas
'artist' is the definition.
(painter Edgar Degas)
'dealers first to back green' is the wordplay.
'dealers first' becomes 'd' (1st letter of 'dealers').
'to back' shows that the letters should be reversed in order.
'green' becomes 'sage' (shade of green).
'sage' back-to-front is 'egas'.
'd'+'egas'='DEGAS'
(Other definitions for degas that I've seen before include "He produced works of art" , "Edgar --, French painter and sculptor" , "Edgar ---, ballet-dancer painter" , "French artist known for his ballet scenes, d.1917" , "He painted dancers" .)