Antibiotic (10)
I believe the answer is:
penicillin
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">antibiotic</span>' is the definition.<br/ ><span class="explanation-format__explanation">(penicillin is a kind of antibiotic)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for penicillin that I've seen before include "17" , "Common antibiotic" .)