Collapse, faint (4,4)
I believe the answer is:
keel over
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">collapse</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">faint</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ ></span>
(Other definitions for keel over that I've seen before include "Suddenly collapse" , "Capsize" , "Fall, as in a faint" , "Pass out" .)