Scottish landowners in Los Angeles — one’s crossing road (6)
I believe the answer is:
lairds
'scottish landowners' is the definition.
('laird' is a Scottish term for a landowner)
'los angeles one's crossing road' is the wordplay.
'los angeles' becomes 'LA' (abbreviation).
'one's' becomes 'i's' (Roman numeral).
'crossing' is an insertion indicator.
'road' becomes 'rd' (abbreviation).
'is' going around 'rd' is 'irds'.
'la'+'irds'='LAIRDS'
'in' acts as a link.
(Other definitions for lairds that I've seen before include "Members of northern gentry" , "Men of property" , "Scottish landowners (6)" , "wealthy Scots?" , "Scots landowners" .)