Be relevant to an eccentric painter (7)
I believe the answer is:
pertain
'be relevant' is the definition.
(I've seen this in another clue)
'an eccentric painter' is the wordplay.
'an eccentric' indicates anagramming the letters.
'painter' anagrammed gives 'PERTAIN'.
'to' is the link.
(Other definitions for pertain that I've seen before include "Relate (to), apply (to)" , "Have relevance" , "Refer" , "Be relevant, or belong as part" , "Be related or applicable (to something)" .)