File uneven spar (4)
I believe the answer is:
rasp
'file' is the definition.
(I know that rasp is a type of file)
'uneven spar' is the wordplay.
'uneven' indicates an anagram.
'spar' is an anagram of 'RASP'.
(Other definitions for rasp that I've seen before include "Grating noise; file" , "It is used to grate" , "sort of berry?" , "unpleasant noise" , "Filing tool" .)