False identity (5)
I believe the answer is:
alias
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">false identity</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 alias that I've seen before include "False or assumed name" , "it may be assumed" , "Otherwise known as" , "Cabbage salad" , "Otherwise - an assumed name" .)