Pole received by more mature artist (3,6)
I believe the answer is:
old master
'artist' is the definition.
(old master is a kind of artist)
'pole received by more mature' is the wordplay.
'pole' becomes 'mast' (mast is a kind of pole).
'received by' indicates putting letters inside.
'more mature' becomes 'older' ('old' is associated in meaning with 'mature').
'mast' inserted within 'older' is 'OLD MASTER'.
(Other definitions for old master that I've seen before include "Costa?" , "great work" , "soon to leave school?" , "special picture" , "Famous painting" .)