Dust to clean with wife away (3)

I believe the answer is:
ash
'dust' is the definition.
(I've seen this before)
'clean with wife away' is the wordplay.
I cannot quite see how this works, but
'away' could be 'a' (abbreviation as used in sports fixtures) and 'a' is present in the answer.
The remaining letters 'sh' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'to' acts as a link.
Can you help me to learn more?
(Other definitions for ash that I've seen before include "Result of burning - deciduous tree" , "Powdery residue from fire or cigarette" , "End of fire" , "Remains from the yule-log?" , "Tree with keys" .)
