Country one visits while I head northwards (7)
I believe the answer is:
tunisia
'country' is the definition.
(Tunisia is an example)
'one visits while i head northwards' is the wordplay.
'one' becomes 'I' (Roman numeral).
'visits' indicates putting letters inside (visit can mean to go into).
'while' becomes 'as'.
'head' becomes 'nut' (informal term for somebody's head).
'northwards' shows that the letters should be reversed in order (in a down clue, letters go up or \'north\').
'as'+'i'+'nut'='asinut'
'i' put inside 'asinut' is 'aisinut'.
'aisinut' reversed gives 'TUNISIA'.
(Other definitions for tunisia that I've seen before include "Country between Algeria/Libya" , "Land" , "N African country in which ancient Carthage lies" , "North African republic" , "country-style" .)