Vehicle returns at eleven (4)
I believe the answer is:
taxi
'vehicle' is the definition.
(I know that taxi is a type of motor car)
'returns at eleven' is the wordplay.
'returns' shows that the letters should be reversed in order.
'eleven' becomes 'xi' (Roman numerals).
'at' in reverse letter order is 'ta'.
'ta'+'xi'='TAXI'
(Other definitions for taxi that I've seen before include "Transport for hire" , "Motor-cab" , "Minicab" , "move on ground before take-off" , "Motor cab" .)