Sound of a maladjusted organ? (5)

I believe the answer is:

groan

I'm a little stuck... Click here to teach me more about this clue!

'sound' is the definition.
(I have seen 'Sound of despair ' mean 'groan' so perhaps 'sound' could also mean 'groan')

'a maladjusted organ?' is the wordplay.
'organ' anagrams to 'GROAN'.
But, I'm not clear how this is indicated.

'of' is the link.

Can you help me to learn more?

(Other definitions for groan that I've seen before include "Complaint" , "Utterance expressing pain or disapproval" , "Sound of pain or disapproval" , "Organ (anag) - lament" , "See 18 Down" .)

I've seen this clue in the Evening Standard.

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