Was single potty adequate receptacle for drinker? (9)
I believe the answer is:
wineglass
'adequate receptacle for drinker?' is the definition.
(receptacle used by someone drinking wine)
'was single potty' is the wordplay.
'potty' indicates an anagram.
'was'+'single'='wassingle'
'wassingle' with letters rearranged gives 'WINEGLASS'.
(Other definitions for wineglass that I've seen before include "possibly held in this port? The opposite" , "Vessel with bowl and stem" .)