Industrial action (6)
I believe the answer is:
strike
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">industrial action</span>' is the definition.<br/ ><span class="explanation-format__explanation">(workers going on strike)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for strike that I've seen before include "Hit; cancel" , "Song of regret" , "Deliver a blow" , "Form of industrial action" , "Sudden attack; chime" .)