a done deal
US /ə dʌn diːl/
UK /ə dʌn diːl/

1.
板上钉钉的事, 已成定局
a final agreement or decision that cannot be changed
:
•
The contract is signed, so it's a done deal.
合同已签署,所以这是板上钉钉的事。
•
Don't worry, the merger is a done deal; the announcement will be made next week.
别担心,合并已经是板上钉钉的事了;下周就会公布。