In actual fact (6)
I believe the answer is:
really
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">in actual fact</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 really that I've seen before include "Undoubtedly" , "Indeed" , "surprised expression" , "Well I never!" , "Genuinely" .)