Metric substitute for the acre (7)
I believe the answer is:
hectare
'metric substitute' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'the acre' is the wordplay.
'the acre' anagrams to 'HECTARE'.
However, I am not sure how the anagram is indicated.
'for' is the link.
Can you help me to learn more?
(Other definitions for hectare that I've seen before include "Amount of ground" , "Some land in France" , "Metric unit of area" , "10,000 square metres" , "10,000 squaer metres" .)