Declared invalid by woman outside university on line leading demonstration (8)

I believe the answer is:

annulled

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

I cannot understand how the rest of the clue works.

(Other definitions for annulled that I've seen before include "Made legally void" , "Cancelled" , "Declared to no longer exist" , "Made invalid" , "Declared invalid" .)

I've seen this clue in the Irish Times (Crosaire) and the Irish Times.

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