Sets aside, it swells in sound (6)

I believe the answer is:

waives

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'sets aside' is the definition.
(I've seen this in another clue)

I cannot understand how the remainder of the clue works.

(Other definitions for waives that I've seen before include "Renounces" , "Relinquishes legal claim to" , "Relinquishes a right" .)

I've seen this clue in the Sydney Morning Herald.

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