Be served rum, eg, in this? Probably something else (4,3)
I believe the answer is:
beer mug
'this? probably something else' is the definition.
The definition suggests a singular noun which matches the answer.
'be served rum eg' is the wordplay.
'served' is an anagram indicator.
'rum'+'eg'='rumeg'
'rumeg' with letters rearranged gives 'ermug'.
'be'+'ermug'='BEER MUG'
'in' acts as a link.
(Other definitions for beer mug that I've seen before include "Drink container" , "Stein or tankard" , "drinking vessel" , "Cup for best" , "glass" .)