Unit of power (4)
I believe the answer is:
watt
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">unit of power</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for watt that I've seen before include "Scottish engineer and inventor, d. 1819" , "SI unit of power" , "Unit of electricity" , "man of power?" , "Worker in steam" .)