Boy stopped by Irish landowner (5)
I believe the answer is:
laird
'landowner' is the definition.
(Scottish term for a landowner)
'boy stopped by irish' is the wordplay.
'boy' becomes 'lad' (lad is a kind of boy**).
'stopped by' is an insertion indicator (I've seen this in other clues).
'irish' becomes 'ir' (abbreviation).
'lad' going around 'ir' is 'LAIRD'.
(Other definitions for laird that I've seen before include "Scots landowner" , "Big landowner" , "rich Scotsman" , "Man owning land" , "One's landed in Scotland" .)