Land unit (4)
I believe the answer is:
acre
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">land unit</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 "point four nought five of a hectare" , "Care about the piece of land" , "Not a lot of land" , "Measure of land area" , "Care about this bit of land" .)