Peacemaking position cut by a reactionary (9)
I believe the answer is:
placatory
'peacemaking' is the definition.
(to placate someone is to attempt to calm them down)
'position cut by a reactionary' is the wordplay.
'position' becomes 'place' (synonyms).
'cut' means to remove the last letter.
'by' becomes 'a' (I am not sure about this - if you are sure you should believe this answer much more).
'a reactionary' becomes 'tory' (both are political right-wingers).
'place' with its final letter taken off is 'plac'.
'plac'+'a'+'tory'='PLACATORY'
(Other definitions for placatory that I've seen before include "Play-actor trying to be conciliatory" , "calming" .)