Detectives offer to take in radical US prisoner (8)

I believe the answer is:

yardbird

'us prisoner' is the definition.
(US term for a prisoner)

'detectives offer to take in radical' is the wordplay.
'detectives' becomes 'yard' (Scotland Yard, Metropolitan Police HQ).
'offer' becomes 'bid' (bid is a kind of offer).
'to take in' is an insertion indicator.
'radical' becomes 'r' (chemistry abbreviation).
'bid' enclosing 'r' is 'bird'.
'yard'+'bird'='YARDBIRD'

I've seen this clue in The Independent.

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