Glaciers (3,6)
I believe the answer is:
ice sheets
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">glaciers</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for ice sheets that I've seen before include "masses of really cold water" , "frozen wastes" .)