Fantastic magician (6)
I believe the answer is:
wizard
This clue is a double definition.
'fantastic' is the first definition.
(I've seen this before)
'magician' is the second definition.
(synonyms)
(Other definitions for wizard that I've seen before include "Male wand-waver" , "Superb" , "Genius" , "A magician, perhaps from Oz" , "speller" .)