A good glass (5)
I believe the answer is:
paste
This could be a double definition.
'a good' is the first definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'glass' is the second definition.
(thesaurus)
Can you help me to learn more?
(Other definitions for paste that I've seen before include "Adhesive, for wallpaper say" , "Watery adhesive" , "Stick - imitation gems" , "Tapes (anag.)" , "Food for spreading or fixative" .)