Game restarts, marred by low frequency fouls (5-4)

I believe the answer is:

bully-offs

'game restarts' is the definition.
(hockey term)

'marred by low frequency fouls' is the wordplay.
I cannot quite see how this works, but
'by' could be 'of' and 'of' is present in the answer.
'frequency' could be 'f' (abbreviation e.g. FM radio) and 'f' is found in the answer.
This explanation may well be incorrect...

I've seen this clue in The Times.

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