Audibly, complaint increased in volume (5)

I believe the answer is:

grown

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'increased in volume' is the definition.
'grown' can be an answer for 'increased' (I've seen this before). I am not sure about the 'in volume' bit.

'audibly complaint' is the wordplay.
'audibly' indicates a 'sounds like' (homophone) clue.
'complaint' becomes 'groan' (I've seen this before).
'groan' sounds like 'GROWN'.

Can you help me to learn more?

(Other definitions for grown that I've seen before include "Wrong (anag)" , "Big" , "Raised; having got bigger" , "Increased; developed" , "Increased; raised" .)

I've seen this clue in The Guardian.

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