Private feud (8)
I believe the answer is:
vendetta
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">private feud</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for vendetta that I've seen before include "Violent quarrel" , "Sicilian blood feud" , "rivalry" , "Violent feud" , "ding-dong battle" .)