SI unit of power (4)
I believe the answer is:
watt
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">si unit of power</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for watt that I've seen before include "James -; Sc. engineer" , "Engineer, coined the term horsepower, d. 1819" , "James - - (Scottish inventor)" , "Unit of electric power" , "Unit of power - Scottish inventor" .)