Cinematic clownfish (4)
I believe the answer is:
nemo
'cinematic clownfish' 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 "Finding -, animated film" , "Fish sought in film" , "Captain brought to book" , "- me impune lacessit (motto of Scotland)" , "Literary captain" .)