Good opposition (3)

I believe the answer is:

bad

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This clue might be a double definition.

'good' is the first definition.
(thesaurus)

'opposition' is the second definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.

Can you help me to learn more?

(Other definitions for bad that I've seen before include "(Of food) decayed" , "Stinking" , "Of poor quality" , "Harmful" , "Rotten, evil" .)

I've seen this clue in the Evening Standard.

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