Oz actor's prepared for punch (4,3)

I believe the answer is:

nail set

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'punch' is the definition.
(I've seen this before)

'oz actor's prepared' is the wordplay.
'oz actor's' becomes 'nail' (I can't justify this - if you can you should give a lot more credence to this answer).
'prepared' becomes 'set' (set up or ready).
'nail'+'set'='NAIL SET'

'for' is the link.

Can you help me to learn more?

(Another definition for nail set that I've seen is " punch".)

I've seen this clue in The Guardian.

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