Sacked no doubt (2,3,3)

I believe the answer is:

in the bag

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

I don't understand how the remainder of the clue works.

(Other definitions for in the bag that I've seen before include "Sacked" , "As good as secured" , "Almost assured of succeeding" , "Where you may find tea" , "You'll find game here" .)

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

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