Certain vessels used at leisure in a non-alcoholic context (3,3)
I believe the answer is:
tea set
'a non-alcoholic context' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'certain vessels used at leisure' is the wordplay.
I cannot quite see how this works, but
'leisure' could be 'ease' (I've seen this before) and 'ease' is found within the answer.
This explanation may well be incorrect...
'in' is the link.
Can you help me to learn more?
(Other definitions for tea set that I've seen before include "Crockery service" , "Collections of cups, saucers etc for serving light meal" , "Estate (anag) - service" , "China for small meal" , "Equipment for an afternoon meal" .)