Drinking glass for stranger (6)
I believe the answer is:
rummer
This clue is a double definition.
'drinking glass' is the first definition.
(rummer is a kind of drinking glass)
'stranger' is the second definition.
('rum' can be a synonym of 'strange')
'for' is the link.
(Other definitions for rummer that I've seen before include "Comparatively quaint" , "Stemmed drinking glass" , "Stranger" , "drinking-vessel" , "glass in the bar" .)