Mound of stones (5)
I believe the answer is:
cairn
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">mound of stones</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 cairn that I've seen before include "Mound of stones on mountain top" , "Agree" , "Heap of stones as a monument" , "Small terrier" , "Man" .)