Small price to pay for some music (4)

I believe the answer is:

song

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'for some music' is the definition.
(song is a kind of music)

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

(Other definitions for song that I've seen before include "Vocal composition" , "Vocal number" , "See 17" , "Melody (which is cheap to go for)" , "Piece of vocal music" .)

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

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