Pass into disuse (5)
I believe the answer is:
lapse
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">pass into disuse</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 lapse that I've seen before include "Slight error due to forgetfulness" , "Loss (in concentration, say?)" , "Cease to be valid" , "Slight error as caused by inattention" , "Pleas about omission" .)