One in the record, as at the Yard (3)

I believe the answer is:

cid

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'the yard' is the definition.
(the CID is based at New Scotland Yard)

'one in the record as' is the wordplay.
'one' becomes 'i' (Roman numeral).
'in the' indicates putting letters inside.
'record as' becomes 'cd' (compact disc. I am not sure about the 'as' bit.).
'i' going into 'cd' is 'CID'.

'at' acts as a link.

Can you help me to learn more?

I've seen this clue in the Evening Standard.

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