Wear down a nail point (6)
I believe the answer is:
abrade
'wear down' is the definition.
(I've seen this before)
'a nail point' is the wordplay.
'nail' becomes 'brad' (a brad is a nail with rectangular cross-section).
'point' becomes 'e' (compass point).
'a'+'brad'+'e'='ABRADE'
(Other definitions for abrade that I've seen before include "Scratch" , "Scrape away, erode" , "Rub off or scrape away" , "Wear away by rubbing (6)" , "A beard (anag.)" .)