Complete cancellation of a golf match? (5,3)

I believe the answer is:

round off

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'complete cancellation of a' is the definition.
I can't tell whether this definition defines the answer.

'golf match?' is the wordplay.
'golf' becomes 'round of golf' (round of golf is a kind of golf).
'match?' becomes 'f' (I can't justify this - if you can you should believe this answer much more).
'roundof'+'f'='ROUND OFF'

Can you help me to learn more?

(Other definitions for round off that I've seen before include "finish" , "Conclude" .)

I've seen this clue in The Globe and Mail.

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