Move away without warning (2,6)
I believe the answer is:
up sticks
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">move away without warning</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 up sticks that I've seen before include "Move house(colloq.)" , "Move away without warning" , "Make off" .)