Bright vehicles going north (5)
I believe the answer is:
smart
'bright' is the definition.
(I know that bright can be written as smart)
'vehicles going north' is the wordplay.
'vehicles' becomes 'trams' (tram is a kind of vehicle).
'going north' is a reversal indicator.
'trams' back-to-front is 'SMART'.
(Other definitions for smart that I've seen before include "Alick" , "Bright; sting" , "Stylish; sting" , "astute" , "Spruce; sting" .)