Spore sacs (4)
I believe the answer is:
asci
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">spore sacs</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 asci that I've seen before include "name for enlarged cells" , "Fungal spore sacs, I sac (anag.)" , "They usually contain eight units" .)