Concerned with open country (8)
I believe the answer is:
republic
'country' is the definition.
(thesaurus)
'concerned with open' is the wordplay.
'concerned with' becomes 're'.
'open' becomes 'public' ('public' can be similar in meaning to 'open').
're'+'public'='REPUBLIC'
(Other definitions for republic that I've seen before include "Nation with a president as head of state" , "State without monarch" , "Pub relic found in a type of government" , "Strange pub relic of a political system" , "State in which the people hold the power" .)