Celebration by editorial of PM, say (5,6)
I believe the answer is:
party leader
'pm say' is the definition.
I know nothing about this answer so I can't judge whether this works.
'celebration by editorial' is the wordplay.
'celebration' becomes 'party' (I've seen this before).
'by' means one lot of letters go next to another.
'editorial' becomes 'leader' (both can mean a type of newspaper article).
'party'+'leader'='PARTY LEADER'
'of' is the link.
Can you help me to learn more?
(Another definition for party leader that I've seen is " Potential PM".)