Turbulent swift-flowing stream (7)
I believe the answer is:
torrent
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">turbulent swift-flowing stream</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 "Heavy stream" , "Overwhelming flow" , "Heavy flow of water" , "Overwhelming outpouring" , "Outburst" .)