Big butte (4)
I believe the answer is:
mesa
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">big butte</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 mesa that I've seen before include "Flat-topped hill with steep sides, common in the southwestern US" , "Flat-topped mountain" , "US steep-sided tableland" , "Flat tableland with steep sides" , "Flat tableland with steep edges" .)