Two males welcoming one making a pile (7)
I believe the answer is:
mansion
'a pile' is the definition.
('pile' can mean a stately home)
'two males welcoming one' is the wordplay.
'two males' can mean two replacements for 'male'.
'male' becomes 'man' (man is a kind of male).
'male' becomes 'son' ().
'welcoming' is an insertion indicator (in sense of 'inviting in').
'one' becomes 'I' (Roman numeral).
'son' going around 'i' is 'sion'.
'man'+'sion'='MANSION'
'making' is the link.
(Other definitions for mansion that I've seen before include "Grand house" , "Impressive house" , "Opulent house" , "Manor house" , "large residence" .)