The nozzle reportedly knows peace (9)
I believe the answer is:
nosepiece
'the nozzle' is the definition.
(I've seen this before)
'reportedly knows peace' is the wordplay.
'reportedly' indicates a 'sounds like' (homophone) clue.
'peace' becomes 'piece' (I am not sure about this - if you are sure you should believe this answer much more).
'knows' is a homophone of 'nose'.
'nose'+'piece'='NOSEPIECE'
Can you help me to learn more?
(Other definitions for nosepiece that I've seen before include "some armour" , "bridge" , "Guard at front" , "Protector" , "Plate covering the hooter" .)