Negotiate - and stand a drink! (5)
I believe the answer is:
treat
This clue is a double definition.
'negotiate' is the first definition.
(I've seen this before)
'stand a drink' is the second definition.
(I've seen this before)
'and' is the link.
(Other definitions for treat that I've seen before include "Buy a drink for, for instance" , "Special delight; handle" , "Act toward or regard in a certain way" , "Care for - pay the bill" , "Give medical care or free meal to" .)