Actively working (2,3,8)
I think it could be either:
at the coalface
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">actively working</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for on duty that I've seen before include "Working at a particular time" , "As working policemen are" , "What working nurses are" , "Engaged in one's regular work" , "(Of soldier) working" .)
(Other definitions for at the coalface that I've seen before include "like worker of mine?" , "Not deskbound" .)