V & A visitor most uncertain (7)

I believe the answer is:

vaguest

'most uncertain' is the definition.
(vague can mean uncertain)

'v a visitor' is the wordplay.
'visitor' becomes 'guest' (guest is a kind of visitor).
'v'+'a'+'guest'='VAGUEST'

(Another definition for vaguest that I've seen is " Least precise".)

I've seen this clue in The Times.

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