See a flier as a villain! (5)
I believe the answer is:
crook
'a villain' is the definition.
(a crook is a villain or criminal)
'see a flier' is the wordplay.
'see' becomes 'C' (the word for the letter, according to Chambers).
'a flier' becomes 'rook' (rook is a kind of birdanimal).
'c'+'rook'='CROOK'
'as' acts as a link.
(Other definitions for crook that I've seen before include "Well, no" , "Something kinky" , "Swindler - crosier - ill (in Australia)" , "Shepherd's staff" , "Twister" .)