Unit of land (4)
I believe the answer is:
acre
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">unit of land</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for acre that I've seen before include "amount of land" , "A state of W Brazil" , "Middle East port" , "in Western Brazil" , "Israeli seaport" .)