To kill.
To do away with.
To settle (a debt) by paying the outstanding amount.
To settle the affairs of (a company), by using its assets to pay its debts.
To convert (assets) into cash; to redeem.
To determine by agreement or by litigation the precise amount of (indebtedness); to make the amount of (a debt) clear and certain.
To keep safe; to defend; to guard; to prevent harm coming to.
To book a passenger on a later flight if there is a chance they will not be able to board their earlier reserved flight.