Pixar clownfish (4)
I believe the answer is:
nemo
'pixar 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 "Jules Verne captain" , "Jules Verne's submarine captain" , "- me impune lacessit (motto of Scotland)" , "commander for the Nautilus" , "Captain brought to book" .)