City of priority (3)
I believe the answer is:
rio
'city' is the definition.
(Rio de Janeiro)
'of priority' is the wordplay.
'of' indicates a hidden word.
'RIO' is hidden in the letters of 'priority'.
(Other definitions for rio that I've seen before include "Manchester United player in South American city, in short?" , "(Golfer) in the sand" , "Erstwhile home of Biggs" , "Spanish word for river" , "old capital" .)