From Longman Dictionary of Contemporary Englishit’s a dealit’s a dealspokenAGREE used to say that you agree to do something OK, it’s a deal. → deal
Examples from the Corpus
it’s a deal• It's a deal considering the formidable size.• It's a deal milder than Arendale and there's ling grows there.• "I'll give you $100 for it." "It's a deal."• All right, it's a deal. 