As a joke (2,3)
I believe the answer is:
in fun
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">as a joke</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 in fun that I've seen before include "to raise a smile?" , "for a laugh" , "Not intended seriously" , "As a joke - not seriously" .)