Intelligent to go back to public transport (5)
I believe the answer is:
trams
'to public transport' is the definition.
(I've seen this before)
'intelligent to go back' is the wordplay.
'intelligent' becomes 'smart' (associated in meaning).
'to go back' shows that the letters should be reversed in order.
'smart' back-to-front is 'TRAMS'.
(Other definitions for trams that I've seen before include "Not seen in London" , "public transport" , "old vehicles" , "silk yarns" , "People movers" .)