a done deal

done deal

Something that has been decided or finalized. Once we sign those papers, the sale of the house will be a done deal. I had no idea I'd have to make more payments to receive the merchandise—I thought it was a done deal!
See also: deal, done

a done deal

If something such as a plan or project is a done deal, it has been completed or arranged and it cannot be changed. He called a journalist to announce that his nomination was a done deal. The pact is far from being a done deal. It must be ratified by the legislative bodies of all three countries.
See also: deal, done