The phrase "to agree a deal" means to come to an agreement or reach an understanding with someone regarding a specific transaction, arrangement, or contract. Full definition
Perhaps most interestingly, the player reportedly wishes to issue a statement declaring that he has not agreed a deal with any club. (hitc.com)
Moreover, the report also mentioned that the player agreed a deal in principle to join the Portuguese boss in summer. (soccerisma.com)
Furthermore, not only must the prosecutor never agree a deal on sentencing with the defendant, neither must it make submissions to the court as to what the sentence should be imposed. (newlawjournal.co.uk)