Possibly Mac’s benefactor, ultimately busy with microphone (10)

I believe the answer is:

patronymic

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'possibly mac's' is the definition.
I can't tell whether this defines the answer.

'benefactor ultimately busy with microphone' is the wordplay.
'benefactor' becomes 'patron' (patron is a kind of benefactor).
'ultimately' indicates one should take the final letters.
'with' means one lot of letters go next to another.
'microphone' becomes 'mic'.
The last letter of 'busy' is 'y'.
'patron'+'y'+'mic'='PATRONYMIC'

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(Other definitions for patronymic that I've seen before include "Name derived from forefather" , "Russian middle name" .)

I've seen this clue in The Times.

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