Large rock (7)
I believe the answer is:
boulder
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">large rock</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for boulder that I've seen before include "Colorado city" , "Large stone" , "Large smooth mass of rock" , "Big rock" , "Large, loose eroded rock" .)