Traveller finished behind passenger terminal (5)
I believe the answer is:
rover
'traveller' is the definition.
(rover is a kind of traveller)
'finished behind passenger terminal' is the wordplay.
'finished' becomes 'over' (similar in meaning).
'behind' means one lot of letters go next to another.
'terminal' suggests the final letters (terminal refers to the end).
The final letter of 'passenger' is 'r'.
'over' put after 'r' is 'ROVER'.
(Other definitions for rover that I've seen before include "Old scout" , "Wanderer, traveller" , "gypsy" , "pirate ship" , "Nomad" .)