Passenger carrier (7)
I believe the answer is:
sidecar
'passenger carrier' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for sidecar that I've seen before include "Cocktail of brandy, orange liqueur and lemon juice" , "Cocktail - cedar is (anag)" , "In which Gromit goes" , "Where a passenger may go" , "Attachment to motorcycle to accommodate passenger" .)