Water tortoise (8)
I believe the answer is:
terrapin
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">water tortoise</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 terrapin that I've seen before include "Give out" , "freshwater creature" , "Hardback" , "Chelonian reptile" , "Swimmer" .)