Westward retreat after conflict is admonished (6)
I believe the answer is:
warned
'admonished' is the definition.
('warn' can be a synonym of 'admonish')
'westward retreat after conflict' is the wordplay.
'westward' says the letters should be written backwards.
'retreat' becomes 'den'.
'after' means one lot of letters go next to another.
'conflict' becomes 'war' (war is a kind of conflict).
'den' backwards is 'ned'.
'ned' put after 'war' is 'WARNED'.
'is' is the link.
(Other definitions for warned that I've seen before include "Notified in advance" , "Cautioned about Andrew" , "Put on the alert" , "Notified of potential danger" .)