Benefactor giving professor gold (5)
I believe the answer is:
donor
'benefactor' is the definition.
(I know that donor is a type of benefactor)
'giving professor gold' is the wordplay.
'giving' says to put letters next to each other.
'professor' becomes 'don' (term for a university professor).
'gold' becomes 'or' ('or' is the heraldic name for gold).
'don' next to 'or' is 'DONOR'.
(Other definitions for donor that I've seen before include "One who gives something" , "Someone providing" , "contributor" , "Supporter" , "Generous type" .)