A social event about five -- daughter got on (8)
I believe the answer is:
advanced
'got on' is the definition.
('advance' can be a synonym of 'get on')
'a social event about five daughter' is the wordplay.
'social event' becomes 'dance' (I've seen this before).
'about' is an insertion indicator.
'five' becomes 'v' (roman numeral).
'daughter' becomes 'd'.
'dance' enclosing 'v' is 'dvance'.
'a'+'dvance'+'d'='ADVANCED'
(Other definitions for advanced that I've seen before include "The latest" , "Precocious" , "not for a beginner" , "Lent - brought forward" , "Foremost" .)