Rabbit's tail (4)
I believe the answer is:
scut
'rabbit's tail' is the definition.
(scut can mean a rabbit's tail)
This is all the clue.
(Other definitions for scut that I've seen before include "Cuts into a small tail" , "Reindeer's tail" , "Small tail as of rabbit" , "Deer's tail" , "Short tail of hare" .)