Country I was the leader of (4)
I believe the answer is:
iran
'country' is the definition.
(Iran is a country)
'i was the leader of' is the wordplay.
'was the leader of' becomes 'ran' (run can mean to organise or lead).
'i'+'ran'='IRAN'
(Other definitions for iran that I've seen before include "Modern name for Persia" , "Formerly Persia" , "Nation" , "Tehran's country" , "Country where ayatollahs replaced a shah" .)