It is located east of southern American county (6)
I believe the answer is:
sussex
'county' is the definition.
(I know that Sussex is a county)
'it is located east of southern american' is the wordplay.
'it is located' becomes 'sex' (I can't justify this - if you can you should believe this answer much more).
'east of' is a charade indicator (letters next to each other) (some letters go to the right of others).
'southern' becomes 's' (abbreviation).
'american' becomes 'us' (abbreviation for United States).
's'+'us'='sus'
'sex' after 'sus' is 'SUSSEX'.
Can you help me to learn more?
(Other definitions for sussex that I've seen before include "Historic county of southern England" , "Southern county, divided into East and West" , "County on the English channel" , "One county cricket team ..." , "Saxon southern county" .)