Visibly, it's where drinkers are left in charge (2,6)
I believe the answer is:
in public
'visibly' is the definition.
(in public view)
'where drinkers are left in charge' is the wordplay.
'where drinkers are' becomes 'in pub' (you might drink in a pub).
'left' becomes 'l' (common abbreviation).
'in charge' becomes 'ic' (abbreviation for 'in charge').
'inpub'+'l'+'ic'='IN PUBLIC'
'it's' acts as a link.
(Other definitions for in public that I've seen before include "Openly, not in private" , "(Done) when others are present" , "for all to see" , "On view" , "Openly, directed to people generally" .)