Not different from this America (4)
I believe the answer is:
same
'not different' is the definition.
('same' is the opposite to 'different')
'from this america' is the wordplay.
'from' indicates the answer is hidden within the clue.
'SAME' can be found hidden inside 'this america'.
(Other definitions for same that I've seen before include "Ditto" , "Equal in amount or value" , "Identical, not different" , "uniform" , "Identical, unchanged" .)