City having foremost of roles in Olympics (3)
I believe the answer is:
rio
'city' is the definition.
(Rio de Janeiro)
'foremost of roles in olympics' is the wordplay.
'foremost of' suggests taking the first letters.
The first letters of 'roles in olympics' is 'RIO'.
'having' acts as a link.
(Other definitions for rio that I've seen before include "(Golfer) in the sand" , "Flying Down to -, Astaire, Rogers film" , "The ... Grande borders Texas and Mexico" , "Manchester United player in South American city, in short?" , "Brazilian city and port" .)