Bear from the South American city is fair game (6)
I believe the answer is:
hoopla
'is fair game' is the definition.
(game played at a fair)
'bear from the south american city' is the wordplay.
'bear' becomes 'pooh' (Winnie the Pooh).
'from the south' shows that the letters should be reversed in order (in a down clue, letters go up).
'american city' becomes 'la' (abbreviation for Los Angeles).
'pooh' written backwards gives 'hoop'.
'hoop'+'la'='HOOPLA'
(Other definitions for hoopla that I've seen before include "Fairground stall attraction" , "Fairground throwing game" , "Fairground game; great excitement" , "game in which all-round achievement is rewarded" , "fuss" .)