Wife of former President tours European nation (6)
I believe the answer is:
brunei
'nation' is the definition.
'wife of former president tours european' is the wordplay.
'wife of former president' becomes 'bruni' (Carla Bruni, wife of Nicolas Sarkozy).
'tours' indicates putting letters inside.
'european' becomes 'e' (abbreviation e.g. EU).
'bruni' enclosing 'e' is 'BRUNEI'.
(Other definitions for brunei that I've seen before include "Ill" , "Sultanate in northwest Borneo" , "Eastern land" , "Southeast Asian sultanate" , "Oil-rich sultanate of Borneo" .)