To provide an excuse for.
To provide an alibi for.
The plea or mode of defense under which a person on trial for a crime proves or attempts to prove being in another place when the alleged act was committed.
An excuse, especially one used to avoid responsibility or blame.
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.