Maelstrom (6)
I believe the answer is:
vortex
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">maelstrom</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that maelstrom can be written as vortex)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for vortex that I've seen before include "Whirl of water or air" , "Whirling mass of wind or water" , "Whirlpool - whirlwind" , "Spinning mass of water or air" , "Whirlpool or the like" .)