Unit of work or energy (3)
I believe the answer is:
erg
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">unit of work</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >'<span class="explanation-format__original">energy</span>' is the second definition.<br/ ><br/ ></span>
(Other definitions for erg that I've seen before include "Energy expended" , "Unit of measurement of work" , "Unit of work (phys.)" , "Amount of work" , "Shifting dunes in Sahara" .)