Large glass (6)
(Other definitions for rummer that I've seen before include "Stemmed drinking glass" , "glass in the bar" , "Stranger" , "drinking-vessel" , "Comparatively quaint" .)
(Other definitions for tumbler that I've seen before include "He performs feats" , "A glass; part of lock" , "will hold water" , "Stemless straight-sided glass" , "A glass; a pigeon" .)