Clownfish of film (4)
I believe the answer is:
nemo
'clownfish of film' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for nemo that I've seen before include "Jules Verne captain" , "Captain of the Nautilus" , "Captain brought to book" , "Fish sought in film" , "Finding -, animated film" .)