Crossword Genius

One can be clean — but not after work? (5)

Ross

I believe the answer is:

sweep

'one can be clean' is the definition.
(as in a clean sweep)

'not after work?' is the wordplay.
I cannot quite see how this works, but
'work?' could be 'w' (physics abbreviation) and 'w' is located in the answer.
The remaining letters 'seep' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...

'but' is the link.

(Other definitions for sweep that I've seen before include "Prize draw" , "Row" , "Stroke at the crease" , "do cleaning" , "clear" .)

I've seen this clue in The Times.
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