Clever flipping vehicles (5)
I believe the answer is:
trams
'vehicles' is the definition.
(tram is a kind of vehicle)
'clever flipping' is the wordplay.
'clever' becomes 'smart' (similar in meaning).
'flipping' shows that the letters should be reversed in order.
'smart' reversed gives 'TRAMS'.
(Other definitions for trams that I've seen before include "old vehicles" , "public transport" , "People movers" , "Not seen in London" , "silk yarns" .)