Rum butler drinks marks glass (7)
I believe the answer is:
tumbler
'glass' is the definition.
(tumbler is a kind of glass)
'rum butler drinks marks' is the wordplay.
'rum' indicates an anagram (rum can mean strange or unusual).
'drinks' indicates putting letters inside (inserted letters are consumed or drunk).
'marks' becomes 'M' (former German currency).
'butler' with letters rearranged gives 'tubler'.
'tubler' going around 'm' is 'TUMBLER'.
(Other definitions for tumbler that I've seen before include "Type of drinking glass" , "appears to be falling" , "A drop from a bar may occupy this" , "spilling its contents?" , "Gymnast with a glass" .)