Wear away by friction (6)
I believe the answer is:
abrade
'wear away by friction' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for abrade that I've seen before include "Scratch" , "Rub off or scrape away" , "Shave" , "Day breaks? > Start as before" , "Chafe" .)