Elected politician has refurbished rising concert venue, God willing (9)
I believe the answer is:
inshallah
'god willing' is the definition.
(Arabic word meaning 'God willing')
'elected politician has refurbished rising concert venue' is the wordplay.
'elected politician' becomes 'in' (in can mean elected or in power).
'refurbished' indicates an anagram.
'rising' is a reversal indicator (going up in a down clue).
'concert venue' becomes 'hall' (as in a concert hall).
'hall' back-to-front is 'llah'.
'has' is an anagram of 'sha'.
'in'+'sha'+'llah'='INSHALLAH'
(Other definitions for inshallah that I've seen before include "If God wills!" , "God willing" .)