Frankenstein's assistant, in film (4)
I believe the answer is:
igor
'frankenstein's assistant in film' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for igor that I've seen before include "Maybe 8 [SIKORSKY]" , "Stravinsky, for example" , "Card game" , "Prince in Borodin's opera" , "Prince --, opera by Borodin" .)