Some of Armenia is agricultural land (4)
I believe the answer is:
farm
'agricultural land' is the definition.
(I've seen this before)
'some of armenia is' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'FARM' can be found hidden inside 'of armenia is'.
(Other definitions for farm that I've seen before include "Manage land for crops or livestock" , "Raise crops/livestock" , "Cultivate the land" , "Ranch" , "Country business" .)