Most of UK in plague (6)

I believe the answer is:

blight

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'plague' is the definition.
(synonyms)

I don't understand the rest of the clue.

(Other definitions for blight that I've seen before include "Disease of plants etc" , "Curse - plague" , "Disease or fungus that withers plants, say potatoes" , "Shrivelling disease" , "Plant disease or malign influence" .)

I've seen this clue in The Sun.

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