Leave quickly (5)
I believe the answer is:
scram
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">leave quickly</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 scram that I've seen before include "Vamoose" , "on your bike!" , "Shoo!" , "Scarper" , "Buzz off!" .)