Activate (7)
I believe the answer is:
trigger
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">activate</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that activate can be written as trigger)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for trigger that I've seen before include "Gun-firing device" , "One pulled to fire" , "Releasing device" , "Roy Rogers' horse" , "Activating device" .)