Area of land teacher cultivated (7)
I believe the answer is:
hectare
'area of land' is the definition.
(hectare is a unit for measuring land area)
'teacher cultivated' is the wordplay.
'cultivated' indicates anagramming the letters.
'teacher' with letters rearranged gives 'HECTARE'.
(Other definitions for hectare that I've seen before include "Amount of ground" , "Surface area equal to 10,000 square meters" , "The race (anag) - unit of area" , "Metric unit of area" , "Ten thousand square metres" .)