Body of people under a single government (6)
I believe the answer is:
nation
'body of people under a single government' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for nation that I've seen before include "Large community in one place under one government" , "A federation of tribes, as Native Americans say" , "Race" , "People of a state" , "Body of people under a single government" .)