Crossword Genius

Remain fair, but refuse to pay penalty (4,4)

Ross

I believe the answer is:

keep fine

'remain fair' is the definition.
(as in weather keeping fine)

'refuse to pay penalty' is the wordplay.
I cannot really understand how this works, but
'penalty' could be 'fine' (a financial penalty) and 'fine' is located in the answer.
The remaining letters 'keep' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...

'but' acts as a link.

I've seen this clue in The Guardian.
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