Replacement for the acre? (7)
I believe the answer is:
hectare
'replacement for the acre' is the definition.
I can't judge whether this definition defines the answer.
'replacement for the acre' is the wordplay.
'replacement for' indicates an anagram.
'the'+'acre'='theacre'
'theacre' anagrammed gives 'HECTARE'.
(Other definitions for hectare that I've seen before include "Surface area equal to 10,000 square meters" , "Metric land area" , "Teacher of metric land measure" , "Amount of ground" , "Extent" .)