Lads take on Irish landowners (6)
I believe the answer is:
lairds
'landowners' is the definition.
(laird is a kind of landowner)
'lads take on irish' is the wordplay.
'take' indicates putting letters inside.
'on irish' becomes 'ir' (abbreviation. I am not sure about the 'on' bit.).
'lads' placed around 'ir' is 'LAIRDS'.
Can you help me to learn more?
(Other definitions for lairds that I've seen before include "Scots landowners" , "Members of northern gentry" , "Important northerners" , "Scottish lords" , "Men of property" .)