Financial backer (6)
'financial backer' is the definition.
(someone providing funding)
This is the entire clue.
'financial backer' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for angel that I've seen before include "Sponsor" , "Heavenely messenger" , "Very helpful person" , "Heavenly body" , "one might be recording" .)