Sweet music (4)

I believe the answer is:

rock

I believe this is a double definition.

'sweet' is the first definition.
(as in a stick of rock)

'music' is the second definition.
(rock music)

(Other definitions for rock that I've seen before include "Big stone - music" , "Music; diamond" , "Swing" , "lull baby to sleep?" , "8 - -" .)

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

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