Drink — and slurp regularly (3)
I believe the answer is:
sup
'drink' is the definition.
(to sup is to drink)
'slurp regularly' is the wordplay.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
The alternate letters of 'slurp' are 'SUP'.
'and' is the link.
(Other definitions for sup that I've seen before include "Eat a late meal; sip" , "Drink; take an evening meal" , "A mouthful of liquid" , "Drink; eat evening meal" , "Drink; take a late meal" .)