Specified day (4)
I believe the answer is:
date
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">specified day</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for date that I've seen before include "Particular day" , "escort" , "Year or day when an event occurred" , "Girlfriend perhaps" , "For example, sell by" .)