Hit the drink (4)
I believe the answer is:
I believe this is a double definition.
'hit' is the first definition.
(I know that slug is a more specific form of the action hit)
'the drink' is the second definition.
(Other definitions for slug that I've seen before include "Bullet; swig" , "Slimy fellow in bed" , "Garden pest - pellet" , "Slimy pest" , "Projectile fired from a gun" .)