Man training harpist - not a benefactor (14)
I believe the answer is:
philanthropist
'a benefactor' is the definition.
(philanthropist is a kind of benefactor)
'man training harpist not' is the wordplay.
'man' becomes 'phil' ().
'training' is an anagram indicator (to train can mean to grow something into a shape).
'harpist'+'not'='harpistnot'
'harpistnot' with letters rearranged gives 'anthropist'.
'phil'+'anthropist'='PHILANTHROPIST'
(Other definitions for philanthropist that I've seen before include "Benefactor" , "Giver to good causes" , "Carnegie, say" , "he's good to us" .)