Lose temper (3,3,3,6)
I believe the answer is:
fly off the handle
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">lose temper</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 fly off the handle that I've seen before include "See red" , "Robin perching on spade may" , "Lose one's temper" , "react angrily" .)