Relating to water (7)
I believe the answer is:
aquatic
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">relating to water</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 aquatic that I've seen before include "Marine plant" , "At home in water" , "Living in/near water" , "Growing or living in water" , "such as teal?" .)