File a nail with end of file (6)
I believe the answer is:
abrade
'file' is the definition.
(thesaurus)
'a nail with end of file' is the wordplay.
'nail' becomes 'brad' (brad is a kind of nail**).
'with' says to put letters next to each other.
'end of' suggests the final letters.
The final letter of 'file' is 'e'.
'a'+'brad'+'e'='ABRADE'
(Other definitions for abrade that I've seen before include "Day breaks? > Start as before" , "Scratch" , "Rub off or scrape away" , "Wear away by erosion" , "Wear away by rubbing (6)" .)