Impenetrable row of crops at one end of the country? (8)
I believe the answer is:
cornwall
'one end of the country?' is the definition.
(county at the southwest point of England)
I can't explain the rest of the clue.
(Other definitions for cornwall that I've seen before include "Duchy" , "Southern English county" , "hilly county" , "Crown all in the English county, strangely" , "Part of 1 25 [KING LEAR]" .)