Unit of land area (7)
(Other definitions for hectare that I've seen before include "Teacher of metric land measure" , "Some land in France" , "Ten thousand square metres" , "The race (anag) - unit of area" , "10,000 square metres" .)
'unit of land area' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for acre that I've seen before include "amount of land" , "Unit of area of 4,840 square yards" , "marine location in Israel" , "Ancient city in Israel" , "Middle East port" .)