Greed a wicked habit that holds painter back (7)
I believe the answer is:
avarice
'greed' is the definition.
(avarice is a kind of greed)
'a wicked habit that holds painter back' is the wordplay.
'wicked habit' becomes 'vice' (I've seen this before).
'that holds' means one lot of letters goes inside another.
'painter' becomes 'RA' (member of the Royal Academy of Arts).
'back' says the letters should be written in reverse.
'ra' backwards is 'ar'.
'vice' going around 'ar' is 'varice'.
'a'+'varice'='AVARICE'
(Other definitions for avarice that I've seen before include "Greed - caviare (anag)" , "Rapacity" , "Greed for gain" , "Insatiable desire for wealth" , "Eager desire" .)