Not passive! (6)
I believe the answer is:
active
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">not passive</span>' is the definition.<br/ ><span class="explanation-format__explanation">('active' is the opposite to 'passive')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for active that I've seen before include "Not passive" , "Busy, not idle" , "Moving frequently" , "Energetic, moving" , "Nimble" .)