Star, Ringo perhaps, announced: 'Good, EU's beginning to evaporate' (10)
I believe the answer is:
betelgeuse
'star' is the definition.
(I know that Betelgeuse is a supergiant)
'ringo perhaps announced good eu's beginning to evaporate' is the wordplay.
'ringo perhaps' becomes 'Beatle' (one of the Beatles).
'announced' shows a homophone (sound like).
'good' becomes 'g' (abbreviation).
'beginning to' says to take the initial letters.
The initial letter of 'evaporate' is 'e'.
'beatle' is a homophone of 'betel'.
'betel'+'g'+'eus'+'e'='BETELGEUSE'
(Other definitions for betelgeuse that I've seen before include "Reddish star in Orion" , "Bright star" .)