Hard work, labour (4)
I believe the answer is:
toil
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">hard 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">labour</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that labour can be written as toil)</span><br/ ><br/ ></span>
(Other definitions for toil that I've seen before include "Hard physical work" , "Work hard and long" , "Work hard, labour" , "Work extremely hard" , "Work really hard" .)