What the witness produced at the bar perhaps for The Confirmation (8)

I believe the answer is:

evidence

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'confirmation' is the definition.
(I've seen this before)

I can't explain the rest of the clue.

(Other definitions for evidence that I've seen before include "Supporting facts" , "Knowledge on which to base belief" , "Testimony - verification" , "Proof; testimony" , "support" .)

I've seen this clue in the Irish Times.

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