Nonsense about a vehicle being strong (6)
I believe the answer is:
robust
'strong' is the definition.
(similar in meaning)
'nonsense about a vehicle' is the wordplay.
'nonsense' becomes 'rot' (rot can mean nonsense or rubbish).
'about' is an insertion indicator.
'a vehicle' becomes 'bus' (public transport vehicle).
'rot' enclosing 'bus' is 'ROBUST'.
'being' is the link.
(Other definitions for robust that I've seen before include "Down-to-earth" , "Full and rich (wine)" , "Forceful" , "Tough!" , "Having a strong constitution" .)