Irish lake (5)
I believe the answer is:
lough
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">irish lake</span>' is the definition.<br/ ><span class="explanation-format__explanation">(Irish term for 'lake')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for lough that I've seen before include "Irish word for lake" , "Irish loch" , "An Irish lake or arm of the sea" , "Body of water" , "Irish term for lake" .)