I note Eastern ruler will accommodate everyone, God willing (9)
I believe the answer is:
inshallah
'god willing' is the definition.
(Arabic word meaning 'God willing')
'i note eastern ruler will accommodate everyone' is the wordplay.
'note' becomes 'n' (abbreviation).
'eastern ruler' becomes 'shah' (historical title of the Iranian monarch).
'will accommodate' means one lot of letters goes inside another (inserted letters are accommodated).
'everyone' becomes 'all' (all people).
'shah' enclosing 'all' is 'shallah'.
'i'+'n'+'shallah'='INSHALLAH'
(Other definitions for inshallah that I've seen before include "God willing" , "If God wills!" .)