Returning at eleven in cab (4)
I believe the answer is:
taxi
'cab' is the definition.
('taxi' can be a synonym of 'cab')
'returning at eleven' is the wordplay.
'returning' is a reversal indicator.
'eleven' becomes 'xi' (roman numeral).
'at' back-to-front is 'ta'.
'ta'+'xi'='TAXI'
'in' acts as a link.
(Other definitions for taxi that I've seen before include "Vehicle that plies for hire" , "At airport, guide" , "Hackney carriage" , "Motor cab" , "Hired vehicle" .)