Person who gives name entering house, say (5)
I believe the answer is:
donor
'person who' is the definition.
'donor' can be an answer for 'person' (donor is a kind of person). I am not sure about the remainder of the definition.
'name entering house say' is the wordplay.
'name' becomes 'don'.
'entering house say' becomes 'or' (I am not sure about this - if you are sure you should believe this answer much more).
'don'+'or'='DONOR'
'gives' acts as a link.
Can you help me to learn more?
(Other definitions for donor that I've seen before include "Benefactor, giver" , "A giver, often of blood" , "One who dishes out" , "Almsgiver, benefactor" , "Supporter" .)