Short opening move by a foreign state (6)
I believe the answer is:
gambia
'foreign state' is the definition.
'short opening move by a' is the wordplay.
'short' means to remove the last letter.
'opening move' becomes 'gambit' (I've seen this before).
'by' is a charade indicator (letters next to each other).
'gambit' with its last letter removed is 'gambi'.
'gambi'+'a'='GAMBIA'
(Other definitions for gambia that I've seen before include "West African country surrounded by Senegal" , "Aim bag toward African state" , "West African country, capital Banjul" , "West African river" .)