Global peacekeepers against entering unstable Israel (9)
I believe the answer is:
universal
'global' is the definition.
(thesaurus)
'peacekeepers against entering unstable israel' is the wordplay.
'peacekeepers' becomes 'un'.
'against' becomes 'v' (abbreviation for 'versus').
'entering' means one lot of letters goes inside another.
'unstable' indicates anagramming the letters.
'israel' with letters rearranged gives 'iersal'.
'v' inserted into 'iersal' is 'iversal'.
'un'+'iversal'='UNIVERSAL'
(Other definitions for universal that I've seen before include "Applying throughout the world" , "Of worldwide scope" , "All-inclusive" , "Ubiquitous" , "Common" .)