Workers' organisations (6)
I believe the answer is:
unions
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">workers' organisations</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 unions that I've seen before include "employee groups" , "Undoes a knot" , "Employee's organisations" , "Trade organisations" , "Marriages or workers' organisations" .)