Ferment (4)
I believe the answer is:
brew
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">ferment</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for brew that I've seen before include "Make beer by boiling and fermentation" , "Prepare (drink of tea)" , "Infusion" , "Prepare by boiling and infusing" , "Ferment rather than distil" .)