Chief financial backer in spirit (9)
I believe the answer is:
archangel
'spirit' is the definition.
(I've seen this before)
'chief financial backer' is the wordplay.
'chief' becomes 'arch' ('arch' can be a synonym of 'chief').
'financial backer' becomes 'angel' (I've seen this before).
'arch'+'angel'='ARCHANGEL'
'in' acts as a link.
(Other definitions for archangel that I've seen before include "celestial flier" , "Highest ranking member of the celestial hierarchy" , "foreign port" , "What we call a port" , "Gabriel, for example" .)