Campaigned showing signs of nervousness (8)

I believe the answer is:

agitated

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'campaigned' is the definition.
Although both the answer and definition are past participle verbs, I can't see how they can define each other.

I don't understand the remainder of the clue.

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(Other definitions for agitated that I've seen before include "in troubled state" , "Upset, disturbed" , "Disturbed - excited" , "Excited or troubled" , "Jittery, hyped up" .)

I've seen this clue in The Telegraph.

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