Wear down a bread roll (6)
I believe the answer is:
abrade
'wear down' is the definition.
(I've seen this in another clue)
'a bread roll' is the wordplay.
'roll' is an anagram indicator.
'bread' with letters rearranged gives 'brade'.
'a'+'brade'='ABRADE'
(Other definitions for abrade that I've seen before include "Wear away by erosion" , "Wear away by rubbing (6)" , "Wear away by friction" , "Wear away by rubbing, scrape" , "Rub off or scrape away" .)