Border controlled by landed gentry
I believe the answer is:
edge
'border controlled by landed gentry' is the definition.
'edge' can be an answer for 'border' (synonyms). I am unsure of the 'controlled by landed gentry' bit.
'border controlled by landed gentry' is the wordplay.
'border' suggests removing the centre (I've seen 'borders of' mean this).
'controlled' becomes 'ensured' ('ensure' can be a synonym of 'control').
'by landed gentry' becomes 'ge' (I can't explain this - if you can you should give a lot more credence to this answer).
'ensured' with its centre removed is 'ed'.
'ed'+'ge'='EDGE'
Can you help me to learn more?
(Other definitions for edge that I've seen before include "Guitarist with U2" , "Outer limit" , "'Margin, rim (4)'" , "Rim or slight advantage" , "Skirt" .)