A Republican chap visiting American state (9)
I believe the answer is:
argentina
'state' is the definition.
(I know that Argentina is a South American country)
'a republican chap visiting american' is the wordplay.
'a republican chap' becomes 'argent' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'visiting' becomes 'in'.
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'argent'+'in'+'a'='ARGENTINA'
Can you help me to learn more?
(Other definitions for argentina that I've seen before include "Ta, Grannie, for the odd country" , "Republic" , "Its capital Buenos Aires" , "South American country" , "part of 18 [SOUTH AMERICA]" .)