A rush of water (7)
I believe the answer is:
torrent
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">a rush of 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 torrent that I've seen before include "Swift or violent stream" , "Flood, spate" , "Inundation" , "Heavy stream" , "Violently fast stream of water" .)