Extensive landed property (6)
I believe the answer is:
estate
'extensive landed property' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for estate that I've seen before include "Housing area" , "What you leave when you die" , "Total possessions" , "Everything one owns -- tea set (anag)" , "Piece of land with a large house or many small ones" .)