On the subject of (5)
I believe the answer is:
about
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">on the subject of</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for about that I've seen before include "'All - - Eve' (film)" , "not far away" , "in action" , "Concerning; approximately" , "Concerning; roughly" .)