Takes drugs (4)
I believe the answer is:
uses
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">takes drugs</span>' is the definition.<br/ ><span class="explanation-format__explanation">(someone who takes drugs is a 'user')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for uses that I've seen before include "Functions, applications" , "Customs" , "'Purposes, functions (4)'" , "Utilises" , "Sues (anag.)" .)