Long live Violet and Virginia (4)
I believe the answer is:
viva
'long live' is the definition.
(I've seen this before)
'violet and virginia' is the wordplay.
'violet' becomes 'vi'.
'and' is a charade indicator (letters next to each other).
'virginia' becomes 'va' (US state abbreviation).
'vi'+'va'='VIVA'
(Other definitions for viva that I've seen before include "Oral examination" , "Long live! - oral exam" , "Kind of exam" , "Hail to the Spaniards" , "test" .)