Fake suffering's called out - Methuselah's full of it (9)
I believe the answer is:
champagne
'it' is the definition.
The definition suggests a singular noun which matches the answer.
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for champagne that I've seen before include "French 'sparkler'" , "White sparkling wine" , "part of France" , "French wine district" , "tipple" .)