The phrase "clinching the deal" typically conveys a sense of success, accomplishment, and finality in closing an important agreement or contract. However, there are several antonyms or opposite phrases that can be associated with this term. For instance, "losing the deal" suggests that the negotiation or sales pitch did not go as planned and the opportunity was missed. "Backing out of the deal" implies that one party reneged on their commitment or deal, and decided against pursuing the agreement. Alternatively, "reopening the deal" might imply that the negotiations were halted or paused for some reason, but can be resumed at a later time.