Transport quick to turn up (5)
I believe the answer is:
trams
'transport' is the definition.
(trams are a type of public transport)
'quick to turn up' is the wordplay.
'quick' becomes 'smart' (I've seen this in another clue).
'to turn up' says the letters should be written in reverse.
'smart' in reverse letter order is 'TRAMS'.
(Other definitions for trams that I've seen before include "People movers" , "public transport" , "silk yarns" , "old vehicles" , "Not seen in London" .)