Fibbing (5)
I believe the answer is:
lying
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">fibbing</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 lying that I've seen before include "Not being disturbed" , "Telling untruths" , "Extending" , "Untruthful - in bed?" , "Anything but upright" .)