A good rebuttal (3)

I believe the answer is:

bad

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This might be a double definition.

'a good' is the first definition.
(thesaurus)

'rebuttal' is the second definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.

Can you help me to learn more?

(Other definitions for bad that I've seen before include "SECOND HALF OF 16" , "Evil, below standard or off" , "Severe; of low standard" , "Of poor quality" , "Wicked" .)

I've seen this clue in the Evening Standard.

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