Cloth rusted away (6)
I believe the answer is:
duster
'cloth' is the definition.
(duster is a kind of cloth)
'rusted away' is the wordplay.
'away' is an anagram indicator (letters move away from their original places).
'rusted' is an anagram of 'DUSTER'.
(Other definitions for duster that I've seen before include "Rusted (anag)" , "cleaner" , "Polishing cloth" , "Soft cloth for cleaning surface" , "Cloth for removing surface powder" .)