Workers' group (5)
I believe the answer is:
union
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">workers' group</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 union that I've seen before include "Group who may want better conditions" , "mating" , "Workers' federation" , "could be seen in middle of Grand Canal" , "The joining of two or more together" .)