Flemish artist Peter Paul __ (6)
I believe the answer is:
rubens
'flemish artist peter paul' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for rubens that I've seen before include "Peter Paul --, artist" , "Peter Paul -, sixteenth to seventeenth century Flemish painter" , "Burnes turns out to be an artist" , "C16-17 Flemish painter" , "Peter Paul -, sixteenth-seventeenth century Flemish painter" .)