Remain fair, but refuse to pay penalty (4,4)
I believe the answer is:
'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.