One's eaten by fat Scot housed in an estate? (5)
I believe the answer is:
laird
'scot housed in an estate?' is the definition.
(a laird is a Scottish landowner)
'one's eaten by fat' is the wordplay.
'one' becomes 'i' (Roman numeral).
'eaten by' is an insertion indicator (inserted letters get eaten).
'fat' becomes 'lard' (lard is a kind of fat).
'i' put into 'lard' is 'LAIRD'.
(Other definitions for laird that I've seen before include "He's landed in Scotland" , "Estate landowner" , "Scottish landowner" , "Big landowner" , "One's landed in Scotland" .)