Drink to slake it (6)
I believe the answer is:
thirst
'drink to slake it' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for thirst that I've seen before include "Strong desire from dehydration?" , "Dryness" , "Craving for liquid" , "Hunger" , "The inducement for 5 Down" .)