I was leader in the country (4)
I believe the answer is:
iran
'the country' is the definition.
(Iran is a country)
'i was leader' is the wordplay.
'was leader' becomes 'ran' (I can't justify this - if you can you should believe this answer much more).
'i'+'ran'='IRAN'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for iran that I've seen before include "Country where the official language is Farsi" , "It used to be Persia" , "Former Persia" , "Modern-day Persia" , "Previously known as Persia" .)