Site incorporating a luxurious dwelling (6)
I believe the answer is:
palace
'luxurious dwelling' is the definition.
(luxurious or majestic residence)
'site incorporating a' is the wordplay.
'site' becomes 'place' (synonyms).
'incorporating' indicates putting letters inside.
'place' going around 'a' is 'PALACE'.
(Other definitions for palace that I've seen before include "Splendid house" , "football team" , "large house" , "Royal house" , "Royal residence" .)