One grabbed by fat landlord (5)
I believe the answer is:
Here is my best explanation:
'landlord' is the definition.
'one grabbed by fat' is the wordplay.
'one' becomes 'i' (Roman numeral).
'grabbed by' means one lot of letters goes inside another.
'fat' becomes 'lard' (I've seen this before).
'i' placed within 'lard' is 'LAIRD'.
(Other definitions for laird that I've seen before include "Scottish estate-owner", "Scot. landowner", "rich Scotsman", "One's landed in Scotland", "Owner of a Scottish estate", "Scottish owner of large estate", "Scots estate owner", "Big landowner", "Scots landowner" and "Estate landowner".)