Different part of America: no, the reverse (7)
I believe the answer is:
another
'different' is the definition.
(synonyms)
'part of america no the reverse' is the wordplay.
'part of' indicates the answer is hidden within the clue.
'ANOTHER' can be found hidden inside 'america no the reverse'.
(Other definitions for another that I've seen before include "Somebody else" , "Additional: alternative" , "Player or person not yet named or selected" , "A different (thing)" , "Additional, one more" .)