Agreement to accept regular risk - that's really surprising (5)
I believe the answer is:
yikes
'really surprising' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.
'agreement to accept regular risk' is the wordplay.
'agreement' becomes 'yes' (saying yes to something).
'to accept' is an insertion indicator.
'regular' means one should take alternating letters.
The alternating letters of 'risk' are 'ik'.
'yes' going around 'ik' is 'YIKES'.
'that's' is the link.
Can you help me to learn more?
(Other definitions for yikes that I've seen before include "Exclamation of surprise or alarm" , "that was hot!" , "Expression of alarm or astonishment" , "Expression of shock" , "Wowee" .)