Celebration for political group (5)
I believe the answer is:
party
I believe this is a double definition.
'celebration' is the first definition.
(I know that celebration can be written as party)
'for political group' is the second definition.
(a political party)
(Other definitions for party that I've seen before include "Shooting weapon" , "Group gathered together for pleasure" , "Political organisation" , "Political group - celebration" , "Social occasion - political group" .)