Energetic ones (7)
I believe the answer is:
dynamos
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">energetic ones</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for dynamos that I've seen before include "Electricity producers" , "highly energetic people" , "Electricity generators or energetic people" .)