At that time (4)
I believe the answer is:
then
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">at that time</span>' is the definition.<br/ ><span class="explanation-format__explanation">(at some former time)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for then that I've seen before include "soon?" , "Consequently" , "Subsequently - previously" , "Once upon a time" , "At that time; next" .)