Was gloomy concerning the vehicle (5)
I believe the answer is:
moped
This clue is a double definition.
'was gloomy' is the first definition.
(I've seen this in another clue)
'the vehicle' is the second definition.
(moped is a kind of vehicle)
'concerning' is the link.
(Other definitions for moped that I've seen before include "Motor vehicle - languished" , "Two-wheeled vehicle" , "means of transport" , "Despaired" , "simple conveyance" .)