Point ring out over a beer (4)
I believe the answer is:
pint
'a beer' is the definition.
(beer is typically served by the pint)
'point ring out' is the wordplay.
'ring' becomes 'O' (letter resembling a ring).
'out' is a deletion indicator.
'point' with 'o' removed is 'PINT'.
'over' is the link.
(Other definitions for pint that I've seen before include "Quantity" , "Unit of capacity" , "Glass of beer (colloq.)" , "Unit of beer" , "The working man's drink measure" .)