Excuse for the absent-minded? (5)

I believe the answer is:

alibi

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'excuse' is the definition.
(excuse given by a suspect in an investigation)

I can't explain the rest of the clue.

(Other definitions for alibi that I've seen before include "it may help you to get off" , "Answer to charge - was somewhere else" , "Defence against accusation - was somewhere else" , "Proof of not being at crime site" , "Sort of explanation" .)

I've seen this clue in The Globe and Mail.

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