A current celebrity turns up filled with success and an excessive feeling of self-importance (8)
I believe the answer is:
egomania
'a current celebrity turns up filled with success and an excessive feeling' is the definition.
I can't tell whether this definition defines the answer.
'self-importance' is the wordplay.
'self' becomes 'ego' (synonyms).
'importance' becomes 'mania' (I can't explain this - if you can you should believe this answer much more).
'ego'+'mania'='EGOMANIA'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for egomania that I've seen before include "Abnormally excessive opinion of oneself, quite mad" , "not caring about others" , "Obsessive self-centredness" , "Obsessive love of oneself" , "Self-obsession" .)