A small drink; the head (6)
I believe the answer is:
noggin
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">a small drink</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">the head</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(noggin is a kind of head)</span><br/ ><br/ ></span>
(Other definitions for noggin that I've seen before include "Head - tot" , "Small amount of alcohol" , "Gill usually" , "Small amount of liquor" , "Small measure of liquid" .)