Global organisation showing steely resolve might unsettle them (7)
I believe the answer is:
unnerve
'steely resolve might unsettle them' is the definition.
I can't tell whether this definition defines the answer.
'global organisation showing' is the wordplay.
'global organisation' becomes 'UN' (United Nations).
'showing' becomes 'nerve' (I can't justify this - if you can you should believe this answer much more).
'un'+'nerve'='UNNERVE'
Can you help me to learn more?
(Other definitions for unnerve that I've seen before include "Rattle" , "Frighten" , "Discourage - demoralise" , "To startle" , "Dishearten - discourage" .)