100 square meters (3)
I believe the answer is:
are
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">100 square meters</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for are that I've seen before include "(They/you/we) exist" , "Exist; square measure" , "live" , "(We/you/they) exist" , "Is, in the plural" .)