Difficult to follow part of film about fish (8)
I believe the answer is:
pilchard
'fish' is the definition.
(pilchard is a kind of fish)
'difficult to follow part of film about' is the wordplay.
'difficult' becomes 'hard' ('hard' can be a synonym of 'difficult'**).
'to follow' says to put letters next to each other.
'part of film' becomes 'clip' (I've seen this before).
'about' says the letters should be written in reverse.
'clip' in reverse letter order is 'pilc'.
'hard' put after 'pilc' is 'PILCHARD'.
(Other definitions for pilchard that I've seen before include "Small marine food fish" , "Edible herring relative" , "Item of seafood" , "Small sea fish related to the herring" , "Small fatty fish, usually tinned" .)