Legendary magician (6)
I believe the answer is:
merlin
'legendary magician' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for merlin that I've seen before include "Wizard; bird of prey" , "Bird of prey - magician" , "one that cast a spell in Arthur's court" , "Flighty type" , "Hawk-like magician of Camelot" .)