Conflict provided communist leader with a world unsettled (4,3)
I believe the answer is:
cold war
'conflict' is the definition.
(cold war is a kind of conflict)
'communist leader with a world unsettled' is the wordplay.
'leader' indicates taking the first letters.
'with' means one lot of letters goes inside another.
'unsettled' indicates anagramming the letters.
The first letter of 'communist' is 'c'.
'world' with letters rearranged gives 'oldwr'.
'a' placed within 'oldwr' is 'oldwar'.
'c'+'oldwar'='COLD WAR'
'provided' is the link.
(Other definitions for cold war that I've seen before include "Conflict without engagement" , "(Freezing?) state of hostility between nations" , "major stand-off" , "State of hostility (rather than hostilities?)" , "Hostile period after 1945" .)