Charitable giver supplying name in entrance (5)
I believe the answer is:
donor
'charitable giver' is the definition.
(I've seen this before)
'name in entrance' is the wordplay.
'name' becomes 'n' (common abbreviation e.g. on forms).
'in' is an insertion indicator.
'entrance' becomes 'door' (door is a kind of entrance).
'n' inserted inside 'door' is 'DONOR'.
'supplying' acts as a link.
(Other definitions for donor that I've seen before include "One who gives blood, for instance" , "Maker of gift" , "Someone providing" , "Charitable giver" , "patron" .)