A bad actor with Oscar from South American city (5)
I believe the answer is:
omaha
'city' is the definition.
(Omaha is an example)
'a bad actor with oscar from south american' is the wordplay.
'a bad actor' becomes 'ham' (I've seen this before).
'with' is a charade indicator (letters next to each other).
'oscar' becomes 'o' (phonetic alphabet: alpha, bravo, charlie etc.).
'from south' says the letters should be written in reverse.
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'ham'+'o'='hamo'
'hamo' reversed gives 'omah'.
'omah'+'a'='OMAHA'
(Other definitions for omaha that I've seen before include "place in Nebraska" , "Where American may work" , "American town" , "Cotton fabric used for curtains and upholstery" , "State [CITY!!!]" .)