Thick sweet liquid (5)
I believe the answer is:
syrup
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">thick sweet liquid</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 syrup that I've seen before include "Sugary ingredient" , "cough mixture?" , "Boiled sugar solution" , "Sticky stuff" , "linctus" .)