Conspiracy surrounding international leader (5)
I believe the answer is:
pilot
'leader' is the definition.
(thesaurus)
'conspiracy surrounding international' is the wordplay.
'conspiracy' becomes 'plot' (a conspiracy is a secret plot).
'surrounding' indicates putting letters inside.
'international' becomes 'i' (abbreviation eg in IMF).
'plot' going around 'i' is 'PILOT'.
(Other definitions for pilot that I've seen before include "He steers ship or plane" , "Controller of aircraft" , "-- Whale; -- light" , "Guide, steer" , "Trial broadcast" .)