Sounds vibrantly happy (5)

I believe the answer is:

purrs

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'sounds' is the definition.
(purring is a kind of sounding)

I cannot understand how the rest of the clue works.

(Other definitions for purrs that I've seen before include "Cat sounds" , "Cats' contented sounds" , "Feline sounds" , "Cats' noises" .)

I've seen this clue in the Evening Standard.

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