Article on revolutionary investor (5)
I believe the answer is:
angel
'investor' is the definition.
(term for a financial backer of new businesses)
'article on revolutionary' is the wordplay.
'article' becomes 'an' (indefinite article).
'on' becomes 'leg' (cricket term).
'revolutionary' says the letters should be written in reverse (letters revolve around).
'leg' backwards is 'gel'.
'an'+'gel'='ANGEL'
(Other definitions for angel that I've seen before include "Investor in a theatrical production" , "Theatre financier" , "Investor for show" , "Old coin; theatre investor" , "Winged spiritual being" .)