Work out one day's been wasted (or two) (5)

I believe the answer is:

deuce

'two' is the definition.
(synonyms)

I don't understand the rest of the clue.

(Other definitions for deuce that I've seen before include "with equal score" , "40 - 40 (tennis)" , "Level of tennis" , "Forty all in tennis" , "Devil" .)

I've seen this clue in The Guardian.

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