Spirit of leading investor (9)
I believe the answer is:
archangel
'spirit' is the definition.
(I've seen this before)
'leading investor' is the wordplay.
'leading' becomes 'arch' (e.g. in arch-enemy).
'investor' becomes 'angel' (term for a financial backer of new businesses).
'arch'+'angel'='ARCHANGEL'
'of' is the link.
(Other definitions for archangel that I've seen before include "one coming from above with message maybe" , "Senior spirit; Russian port" , "Russian city" , "Most important of divine messengers" , "What we call a port" .)