Welles of filmdom (5)
I believe the answer is:
orson
'welles of filmdom' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for orson that I've seen before include ". . . . . Welles, creator of film ''Citizen Kane''" , "-- Welles, director/actor" , "- - Welles (actor)" , "Film director so-called" , "- - Welles (films)" .)