Hold (down) (3)
I believe the answer is:
pin
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">hold down</span>' is the definition.<br/ ><span class="explanation-format__explanation">(as in pinning down)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for pin that I've seen before include "Fasten; a security code" , "Small object to fasten or attach" , "Peg or nail" , "Skittle; fix" , "Sewer's aid" .)