The land one managed (4)
I believe the answer is:
iran
'the land' is the definition.
(Iran is an example)
'one managed' is the wordplay.
'one' becomes 'i' (Roman numeral).
'managed' becomes 'ran' (both can mean organised or was in charge of).
'i'+'ran'='IRAN'
(Other definitions for iran that I've seen before include "Country lying to south of Caspian sea" , "Former Persia" , "Persia today" , "Modern name for Persia" , "It was known as Persia until 1935" .)