Sound of some tartlets being cooked (6)

I believe the answer is:

rattle

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'sound' is the definition.
(I know that rattle is a type of sound)

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

(Other definitions for rattle that I've seen before include "Let rat make the sound" , "Noisy type of snake" , "Vibrate noisily" , "Disconcert - conductor, Simon" , "making one upset" .)

I've seen this clue in the Evening Standard.

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