Quaff (4)
I believe the answer is:
swig
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">quaff</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that quaff can be written as swig)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for swig that I've seen before include "Gulp of drink" , "Glug" , "Drink deeply" , "Drink (a deep draught)" , "Large swallow" .)