Animal's appendage (4)
I believe the answer is:
tail
'animal's appendage' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tail that I've seen before include "bum" , "Follow - rear part of aeroplane" , "part of coat" , "Follow furtively like private detective" , "Comet's luminous trail" .)