Cambridgeshire City turned over in rugby league (3)
I believe the answer is:
ely
'cambridgeshire city' is the definition.
(Ely is a city in Cambridgeshire)
'turned over in rugby league' is the wordplay.
'turned over' shows that the letters should be reversed in order.
'in' says the answer is hidden in the clue.
'yle' is hidden in the letters of 'rugby league'.
'yle' written backwards gives 'ELY'.
(Other definitions for ely that I've seen before include "UK city" , "Cambs diocese" , "Cathedral city in East Anglia" , "Fenland city" , "Cambs cathedral" .)