US grassland (7)
I believe the answer is:
prairie
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">us grassland</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 prairie that I've seen before include "Treeless grassy plain, in the old West perhaps" , "-- Dog; -- oyster" , "this oyster produces an egg" , "Wide grassy plain" , "Continental grassland of N America" .)