Indulged very large group with grandiose finale in CD (8)
I believe the answer is:
cosseted
'indulged' is the definition.
('cosset' can be a synonym of 'indulge')
'very large group with grandiose finale in cd' is the wordplay.
'very large' becomes 'os' (abbreviation for oversize).
'group' becomes 'set' (set is a kind of group**).
'with' is a charade indicator (letters next to each other).
'finale' indicates one should take the final letters.
'in' is an insertion indicator.
The last letter of 'grandiose' is 'e'.
'os'+'set'+'e'='ossete'
'ossete' placed into 'cd' is 'COSSETED'.
(Other definitions for cosseted that I've seen before include "Pampered, spoiled" , "'Mollycoddled, pampered (8)'" .)