Imperial land measures (5)

I believe the answer is:
acres
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">imperial land measures</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 acres that I've seen before include "Extensive landed property (often rolling)" , "fields?" , "Rival played" , "large area of land" , "farmland maybe?" .)