Regard as something to have up your sleeve? (5)

I believe the answer is:

watch

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'regard' is the definition.
(thesaurus)

I cannot understand how the remainder of the clue works.

(Other definitions for watch that I've seen before include "Keep an eye on - timepiece" , "View" , "Observe - timepiece" , "Keep under observation" , "Observe - guard" .)

I've seen this clue in the Evening Standard.

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