Elongated appendage of an animal (4)
I believe the answer is:
tail
'elongated appendage of an animal' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for tail that I've seen before include "Shadow" , "Private investigator" , "Follow furtively like private detective" , "weaker batsmen" , "Animal's elongated appendage" .)