Concrete last of farm's land (5)
I believe the answer is:
realm
'land' is the definition.
(I've seen this before)
'concrete last of farm's' is the wordplay.
'concrete' becomes 'real' (similar in meaning).
'last of' says to take the final letters.
The last letter of 'farm' is 'm'.
'real'+'m'='REALM'
(Other definitions for realm that I've seen before include "Area of interest/activity" , "World" , "department" , "Kingdom or sphere" , "field of study" .)