A crushing remark you consign to paper (3-4)
I believe the answer is:
put-down
'a crushing remark' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for put-down that I've seen before include "Humiliating remark" , "Snub" , "Crushing remark" .)