Undermine a deal? (10)

I believe the answer is:

compromise

I believe this is a double definition.

'undermine' is the first definition.

'a deal?' is the second definition.
(thesaurus)

(Other definitions for compromise that I've seen before include "Middle course" , "Trade-off" , "Settlement" , "Agree a middle way" , "Settle by concession" .)

I've seen this clue in The Sunday Times and The Times.

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