Sophisticated Count in possession of vehicle going to Clare (8)
I believe the answer is:
advanced
'sophisticated' is the definition.
('advanced' can be similar in meaning to 'sophisticated')
'count in possession of vehicle going to clare' is the wordplay.
'count' becomes 'add' (adding is a kind of counting).
'in possession of' means one lot of letters goes inside another (has inside).
'vehicle' becomes 'van' (van is a kind of vehicle).
'going to' is a charade indicator (letters next to each other).
'clare' becomes 'ce' (I've seen this in other clues).
'van'+'ce'='vance'
'add' going around 'vance' is 'ADVANCED'.
(Other definitions for advanced that I've seen before include "not for a beginner" , "Lent - ahead in development" , "promoted" , "Submitted" , "Moved forward" .)