Owner of estate left thoroughfare, accepting fine (5)
I believe the answer is:
laird
'owner of estate' is the definition.
(I've seen this before)
'left thoroughfare accepting fine' is the wordplay.
'left' becomes 'l' (common abbreviation).
'thoroughfare' becomes 'rd' (abbreviation for road).
'accepting' is an insertion indicator (inserted letters are accepted).
'fine' becomes 'ai' (resembles A1, informal term for top quality).
'l'+'rd'='lrd'
'lrd' placed around 'ai' is 'LAIRD'.
(Other definitions for laird that I've seen before include "Proprietor" , "Estate landowner" , "rich Scotsman" , "Big landowner" , "Scottish estate-owner" .)