All sides except West admit defeat, mostly settled (9)
I believe the answer is:
ensconced
'settled' is the definition.
('ensconce' can be a synonym of 'settle')
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for ensconced that I've seen before include "in safe seat" , "Safely established" , "Settled comfortably" , "Installed" .)