Objectives of European nations disturbed some leaders (4)
I believe the answer is:
ends
'objectives' is the definition.
(end can mean a goal or objective)
'european nations disturbed some leaders' is the wordplay.
'leaders' says to take the initial letters.
The initial letters of 'european nations disturbed some' is 'ENDS'.
'of' acts as a link.
(Other definitions for ends that I've seen before include "ambitions" , "Terminates in dens" , "Brings to a close" , "Stops in dens" , "limits" .)