Knock successful song (3)

I believe the answer is:

hit

This clue is a double definition.

'knock' is the first definition.
('hit' can be a synonym of 'knock')

'successful song' is the second definition.
(I've seen this before)

(Other definitions for hit that I've seen before include "Chart topper" , "suit" , "Badly affected" , "Successful record" , "Popular song; strike" .)

I've seen this clue in The Telegraph.

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