Need to drink (6)
I believe the answer is:
thirst
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">need to drink</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for thirst that I've seen before include "T-shirt (anag)" , "Want of drink" , "Quaff to slake it" , "Strong need for drink" , "A craving for drink or knowledge" .)