I knew leader would interrupt agreement with a cry of alarm (5)
I believe the answer is:
yikes
'i knew leader would interrupt' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.
'agreement with a cry of alarm' is the wordplay.
'agreement' becomes 'yes' (saying yes to something).
'with' is an insertion indicator.
'a cry of alarm' becomes 'ik' (I am not sure about this - if you are sure you should believe this answer much more).
'yes' going around 'ik' is 'YIKES'.
Can you help me to learn more?
(Other definitions for yikes that I've seen before include "Expression of alarm or astonishment" , "Gosh! - Oh no!" , "Exclamation of surprise or alarm" , "Expression of shock" , "alarmed expression" .)