Possibly ruder to an artist! (5)
I believe the answer is:
Here is my best explanation:
'an artist' is the definition.
(I've seen this before)
'possibly ruder' is the wordplay.
'possibly' indicates an anagram.
'ruder' is an anagram of 'DURER'.
'to' is the link.
(Other definitions for durer that I've seen before include "Old master", "From Renaissance artist", "Albrecht -, Ger. artist", "C Fifteenth-Sixteenth German painter/engraver", "Albrecht -, Nuremburg artist", "Painter", "Albrecht -, fifteenth to sixteenth century German artist", "Albrecht --, German painter and engraver", "Albrecht -, C15-16 German artist" and "Renaissance painter".)