Rag rusted away (6)
I believe the answer is:
duster
'rag' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'rusted away' is the wordplay.
'away' indicates anagramming the letters (letters move away from their original places).
'rusted' anagrammed gives 'DUSTER'.
Can you help me to learn more?
(Other definitions for duster that I've seen before include "Cloth for removing surface powder" , "Cloth for cleaning chalk from blackboard" , "yellow cloth" , "cleaner" , "Rusted (anag)" .)