At that party hosting group of stars, I'm leaving (6-2)
I believe the answer is:
toodle-oo
'i'm leaving' is the definition.
I can't judge whether this definition defines the answer.
'at that party hosting group of stars' is the wordplay.
'at that' becomes 'too' (used for emphasis eg 'and a cheap one at that').
'party' becomes 'do' (do is a kind of party).
'hosting' is an insertion indicator (inserted letters are welcomed in or hosted).
'group of stars' becomes 'Leo' (constellation).
'do' going around 'leo' is 'dleoo'.
'too'+'dleoo'='TOODLE-OO'
Can you help me to learn more?
(Other definitions for toodle-oo that I've seen before include "Goodbye (dated)" , "See you later!" , "Farewell (old inf.)" , "Ta-ta" , "Bye-bye!" .)