One age Edward filled with fizz (7)
I believe the answer is:
aerated
'filled with fizz' is the definition.
(I've seen this in another clue)
'one age edward' is the wordplay.
'one' becomes 'a' (a thing is one thing).
'age' becomes 'era' (both can mean a long time).
'edward' becomes 'ted'.
'a'+'era'+'ted'='AERATED'
(Other definitions for aerated that I've seen before include "Mixed with air" , "(Of liquid) charged with gas" , "Descriptive of soda-water" , "Ventilated" , "pumped up" .)