Sign off on

AGREETO

Think of the two words you’d use to accept terms before hitting "submit" on a contract.

"Sign off on" is a phrase that can mean to approve or give consent to something. In crosswords, it’s often clued as a way to hint at "agree to," where "agree" means to accept and "to" is a preposition leading into the action. The phrasing plays on the idea of formally endorsing or authorizing, making "AGREETO" a concise fit for the answer.