Absent without leave (4)
I believe the answer is:
awol
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">absent without leave</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 awol that I've seen before include "gone missing" , "Truant (or just missing)" , "Take unofficial leave (abbrev.)" , "Absent without leave (abbrev.)" , "Absent without leave (abbr.)" .)