After excluding two unknowns, group of stars party (4)
I believe the answer is:
gala
'party' is the definition.
(I've seen this before)
'after excluding two unknowns group of stars' is the wordplay.
I cannot quite understand how this works, but
'after' could be 'ala' ('a la' - 'in the style of ' or 'after' in French) and 'ala' is located in the answer.
'group of' could be 'g' (eg the G7 nations, Group of Seven) and 'g' is found in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for gala that I've seen before include "Public festivity" , "Special sports event" , "A festive occasion, perhaps of sporting nature" , "Special performance" , "Festive occasion - variety of apple" .)