US city minister returning to study (6)
I believe the answer is:
denver
'us city' is the definition.
(capital of Colorado)
'minister returning to study' is the wordplay.
'minister' becomes 'rev' (short for reverend).
'returning' shows that the letters should be reversed in order.
'to' means one lot of letters go next to another (I've seen this in other clues).
'study' becomes 'den' (term for a study or office).
'rev' backwards is 'ver'.
'ver' after 'den' is 'DENVER'.
(Other definitions for denver that I've seen before include "US state capital" , "Capital of Colorado state" , "Country singer and Colorado city" , "Capital of Colorado, USA" , "Capital city of Colorado" .)