In the words of the peacemaker, add ice (4,2)
I believe the answer is:
cool it
'in the words of the peacemaker add' is the definition.
I can't tell whether this definition defines the answer.
'ice' is the wordplay.
I cannot quite see how this works, but
'ice' could be 'cool' (I've seen this in another clue) and 'cool' is present in the answer.
The remaining letters 'it' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for cool it that I've seen before include "Here's what to do before opening champagne" , "Don't get so excited'" , "Relax" , "Modern injunction to calm down" , "Calm down - not so hot." .)