Hospital supplies (4)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">hospital supplies</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for sera that I've seen before include "Sear with serums" , "Bodily fluids (following 'que'?)" , "Watery liquids" , "Hospital supplies" .)