Fix set when winning (5,2)

I believe the answer is:

ready up

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'fix' is the definition.
(thesaurus)

'set when winning' is the wordplay.
I cannot quite see how this works, but
'set' could be 'ready' (similar in meaning) and 'ready' is found in the answer.
'winning' could be 'up' (eg being up at half time in football) and 'up' is found within the answer.
This accounts for all the letters.
This explanation may well be incorrect...

Can you help me to learn more?

I've seen this clue in The Irish Times.

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