Otherwise known as (5)
I believe the answer is:
alias
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">otherwise known as</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 alias that I've seen before include "Also known as" , "Otherwise known as" , "stage name, perhaps" , "aka" , "Otherwise - an assumed name" .)