The term "clinches deal" is an expression used to describe a successful negotiation or agreement between two parties. Some antonyms for this term could be "aborts agreement," "fails negotiation," or "breaks off deal." In these cases, the parties were not able to come to an agreement or a satisfactory outcome despite their efforts. Other antonyms for "clinches deal" might include "unsuccessful bargaining," "unproductive discussion," or "unresolved negotiations." These phrases imply that no deal was made and both parties were unable to reach a consensus or make progress towards a common goal.