Airport shuttle (4)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
tram
'airport shuttle' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tram that I've seen before include "It runs on rails" , "Passenger vehicle on rails" , "Electric vehicle" , "Old city transport, ram on rails through streets" , "Streetcar" .)