Flier is about film (6)
I believe the answer is:
siskin
'flier' is the definition.
(siskin is a kind of birdanimal)
'is about film' is the wordplay.
'about' says the letters should be written in reverse.
'film' becomes 'skin' (I've seen this in other clues).
'is' back-to-front is 'si'.
'si'+'skin'='SISKIN'
(Other definitions for siskin that I've seen before include "Finch akin to canary" , "Little bird" , "Singer" , "Winger" , "Type of finch" .)