Cleaning item rusted away (6)
I believe the answer is:
duster
'cleaning item' is the definition.
'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 "yellow cloth" , "Cloth for removing surface powder" , "Cloth for cleaning chalk from blackboard" , "cleaner" , "Rusted (anag)" .)