Rogue, not initially a supporter of the arts? (5)
I believe the answer is:
easel
'a supporter of the arts?' is the definition.
(I've seen this before)
'rogue not initially' is the wordplay.
'rogue' becomes 'weasel'.
'not initially' means to remove the first letter.
'weasel' with its first letter taken off is 'EASEL'.
(Other definitions for easel that I've seen before include "Painter's stand" , "Painter's support" , "Picture support" , "Standing supporter" , "The rest of artists" .)