3 sound sheepish about arrest (6)

I believe the answer is:

banaba

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'3 sound' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.

'sheepish about arrest' is the wordplay.
'sheepish' becomes 'baa' (I can't justify this - if you can you should give a lot more credence to this answer).
'about' is an insertion indicator.
'arrest' becomes 'nab' (synonyms).
'baa' going around 'nab' is 'BANABA'.

Can you help me to learn more?

I've seen this clue in The Independent.

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