Worn away (6)
I believe the answer is:
eroded
'worn away' is the definition.
('erode' can be a synonym of 'wear away')
This is the entire clue.
(Other definitions for eroded that I've seen before include "Eaten away" , "Worn away, ground down" , "Worn away by time, wind or water" , "Wore away" , "Worn away by weather or water" .)