One in line at an airport (3)
I believe the answer is:
cab
'one in line at an airport' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for cab that I've seen before include "Hackney" , "Driving compartment" , "Transport" , "vehicle" , "It has the authority to confiscate the proceeds of crime, in short" .)