A generous source (5)
I believe the answer is:
donor
This clue could be a double definition.
'a generous' is the first definition.
(I've seen this in another clue)
'source' is the second definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
Can you help me to learn more?
(Other definitions for donor that I've seen before include "Charitable giver" , "Sponsor" , "blessed person, relatively" , "One giving to a cause" , "One who gives something" .)