Science of drugs (12)
I believe the answer is:
pharmacology
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">science of drugs</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 pharmacology that I've seen before include "Branch of medicine concerned with drugs" , "Science of drugs" , "Study of drugs" .)