Conflict with knight brings alert (4)
I believe the answer is:
warn
'alert' is the definition.
(I've seen this before)
'conflict with knight' is the wordplay.
'conflict' becomes 'war' (war is a kind of conflict).
'with' means one lot of letters go next to another.
'knight' becomes 'n' (chess abbreviation).
'war'+'n'='WARN'
'brings' is the link.
(Other definitions for warn that I've seen before include "Sound the alarm" , "Give a caution to" , "Admonish, caution" , "Give advance notice to" , "Notify of potential risk" .)