Endless hell with weed in area of land (7)
I believe the answer is:
hectare
'area of land' is the definition.
(hectare is a unit for measuring land area)
'endless hell with weed' is the wordplay.
'endless' means to remove the last letter.
'hell' becomes 'heck' (interjections!).
'with' is a charade indicator (letters next to each other).
'weed' becomes 'tare' (I've seen this before).
'heck' with its final letter taken off is 'hec'.
'hec'+'tare'='HECTARE'
'in' acts as a link.
(Other definitions for hectare that I've seen before include "The race (anag) - unit of area" , "10,000 squaer metres" , "Metric unit of area" , "Teacher of metric land measure" , "Metric land area" .)