Star is given fixed allowance for festivity (11)
I believe the answer is:
celebration
'for festivity' is the definition.
(synonyms)
'star is given fixed allowance' is the wordplay.
'star' becomes 'celeb' (I've seen this before).
'is given' is a charade indicator (letters next to each other).
'fixed allowance' becomes 'ration' (a fixed quota given out to someone).
'celeb'+'ration'='CELEBRATION'
(Other definitions for celebration that I've seen before include "Jollification" , "The marking of a significant event" , "Festivity to mark a happy event" , "Festive honouring" , "Festival" .)