Call off or invalidate (6)

I believe the answer is:

cancel

I believe this clue is a double definition.

'call off' is the first definition.
(synonyms)

'invalidate' is the second definition.
(I know that invalidate can be written as cancel)

(Other definitions for cancel that I've seen before include "Discontinue" , "stop?" , "Strike out" , "Annul or rescind" , "Scrap" .)

I've seen this clue in The Irish Times.

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