Painter or professional performer for the most part (6)
I believe the answer is:
artist
'painter' is the definition.
(I've seen this before)
'professional performer for the most part' is the wordplay.
'professional performer' becomes 'artiste' (I've seen this before).
'for the most part' means to remove the last letter.
'artiste' with its last letter taken off is 'ARTIST'.
'or' is the link.
(Other definitions for artist that I've seen before include "Painter in dire strait" , "Strait (anag)" , "Skilful, imaginative, performer" , "Constable possibly" , "Eg, a painter" .)