It has a peaceful end (3)
I believe the answer is:
war
'peaceful end' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'it has a' is the wordplay.
'it' becomes 'wr' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'has' is an insertion indicator.
'wr' placed around 'a' is 'WAR'.
Can you help me to learn more?
(Other definitions for war that I've seen before include "series of engagements" , "Armed hostility" , "Large-scale conflict" , "Hostile situation" , "Fight" .)