Swoop (on) (6)
I believe the answer is:
pounce
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">swoop on</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for pounce that I've seen before include "Suddenly spring; fine powder" , "Spring (on prey like a cat)" , "Jump down on suddenly" , "(Of cat) sudden leap to seize prey" , "Jump or spring down as on prey" .)