The weak half of bitter, means to imbibe (6)

I believe the answer is:

watery

I'm a little stuck... Click here to teach me more about this clue!

'the weak' is the definition.
(thesaurus)

I cannot understand how the remainder of the clue works.

(Other definitions for watery that I've seen before include "Aqueous" , "Dilute; weak, pale" , "Weak, too diluted" , "Insipid" , "Overly diluted, thin" .)

I've seen this clue in the Evening Standard.

Want a hint initially instead of a full solution? Install my app