Italian stream (7)
I believe the answer is:
rubicon
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">italian 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 rubicon that I've seen before include "Caeser crossed this river in a decisive step- no going back" , "River, its crossing decisive" , "Italian stream" , "cause of conflict when crossed" , "Polish picture depicting ancient" .)