Aquatic creature (5)
I believe the answer is:
otter
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">aquatic creature</span>' is the definition.<br/ ><span class="explanation-format__explanation">(animal that lives by water)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for otter that I've seen before include "Freshwater brown carnivore" , "Freshwater mammal with dark brown fur" , "Holt dweller" , "Aquatic river mammal" , "eg Tarka" .)