Mixed conditions in the country (6,6)
I believe the answer is:
united states
'country' is the definition.
(I know that United States is a great power)
'mixed conditions' is the wordplay.
'mixed' becomes 'united' (uniting is a kind of mixing).
'conditions' becomes 'states' (I've seen this in another clue).
'united'+'states'='UNITED STATES'
'in the' is the link.
(Other definitions for united states that I've seen before include "National federation" , "Country, capital Washington DC" .)