Hill of sand (4)
I believe the answer is:
dune
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">hill of sand</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 dune that I've seen before include "Mound of drifted sand" , "Nude in the sand" , "Sandhill" , "Sandy hill" , "Low hill of sand, called in a desert a barkhan" .)