Person who opposes stagnation in a panic (10)

I believe the answer is:

antagonist

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'person who opposes' is the definition.
'antagonist' can be an answer for 'person' (antagonist is a kind of person). I am not sure about the rest of the definition.

'stagnation in a panic' is the wordplay.
'in a panic' is an anagram indicator.
'stagnation' anagrammed gives 'ANTAGONIST'.

Can you help me to learn more?

(Other definitions for antagonist that I've seen before include "5 down (anag)" , "Opponent" , "Adversary" , "rival" , "Hostile person" .)

I've seen this clue in The Telegraph.

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