Go off duty (5,4)
I believe the answer is:
stand down
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">go off duty</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 stand down that I've seen before include "Withdraw voluntarily, from job or competition" , "Leave the witness box" , "Exhibition equipment packed up" , "Relinquish one's post" , "Quit" .)