Arthurian sorcerer (6)
I believe the answer is:
merlin
'arthurian sorcerer' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for merlin that I've seen before include "one that cast a spell in Arthur's court" , "small aggressive bird of prey" , "Legendary magician" , "Bird of prey - magician" , "Magician of the Round Table" .)