Beaker allowed to touch mouth (6)
I believe the answer is:
goblet
'beaker' is the definition.
(thesaurus)
'allowed to touch mouth' is the wordplay.
'allowed' becomes 'let' (to let is to allow or permit).
'to touch' says to put letters next to each other.
'mouth' becomes 'gob' (informal term for the mouth).
'let' after 'gob' is 'GOBLET'.
(Other definitions for goblet that I've seen before include "Large drinking cup" , "Bowl-shaped drinking vessel" , "Drinking-glass with stem and foot" , "Chalice" , "Large handleless drinking-cup" .)