Quantity of drink allowed after toilet put back (6)
I believe the answer is:
goblet
'quantity of drink' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'allowed after toilet put back' is the wordplay.
'allowed' becomes 'let' (to let is to allow or permit).
'after' is a charade indicator (letters next to each other).
'toilet' becomes 'bog' (informal term for toilet).
'put back' is a reversal indicator.
'bog' written backwards gives 'gob'.
'let' after 'gob' is 'GOBLET'.
Can you help me to learn more?
(Other definitions for goblet that I've seen before include "Stemmed drinking glass" , "Large drinking cup" , "Drinking-glass with stem and foot" , "Large handleless drinking-cup" , "Bowl-shaped drinking vessel" .)