A number required for identification (3)

I believe the answer is:

I believe this is a double definition.

'a number' is the first definition.
(I know that PIN is a type of number)

'identification' is the second definition.
(I know that PIN is a type of number)

'required for' is the link.

(Other definitions for pin that I've seen before include "Peg or nail" , "Badge" , "Needle" , "Tack; fasten" , "Hold (down)" .)

I've seen this clue in the Evening Standard.

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