Light units (6)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">light units</span>' is the definition.<br/ ><span class="explanation-format__explanation">(lumen is a kind of light unit)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for watts that I've seen before include "rates of working" , "Sculptor" , "Power units (lighting)" , "G. F. -, Eng. artist; power units" , "Rolling Stones drummer?" .)