Whittles (down) (5)
I believe the answer is:
pares
'whittles down' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for pares that I've seen before include "Trims by cutting away" , "Trims, say a pencil" , "Sharpens like pencil" , "Sharpens in spare way" , "Trims by cutting as with pencil" .)