Punishing sort of music? (3)

I believe the answer is:

rap

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'sort of music?' is the definition.
(I've seen this before)

I don't understand how the remainder of the clue works.

(Other definitions for rap that I've seen before include "Criminal charge" , "Administer sharp blow, being below par" , "Knock; type of rhythmical speech to music" , "Knock, tap" , "Sharply criticise" .)

I've seen this clue in the Evening Standard.

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