Almost home, not from South American city (7)
I believe the answer is:
houston
'american city' is the definition.
(I know this)
'almost home not from south' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'home' becomes 'house' (I've seen this in other clues).
'from south' shows that the letters should be reversed in order.
'not' in reverse letter order is 'ton'.
'house' with its final letter taken away is 'hous'.
'hous'+'ton'='HOUSTON'
(Other definitions for houston that I've seen before include "Texan port" , "Whitney ---, US singer" , "One of NASA's locations" , "American city" , "American place" .)