Swaggering Virginia bolsters underwear before party (7)
I believe the answer is:
bravado
'swaggering' is the definition.
(I've seen this before)
'virginia bolsters underwear before party' is the wordplay.
'virginia' becomes 'va' (US state abbreviation).
'bolsters underwear' becomes 'bra' (I can't justify this - if you can you should give a lot more credence to this answer).
'before' means one lot of letters go next to another.
'party' becomes 'do' (do can informally mean a party).
'va' put after 'bra' is 'brava'.
'brava'+'do'='BRAVADO'
Can you help me to learn more?
(Other definitions for bravado that I've seen before include "Swag" , "Swaggering confidence" , "Showy boldness" , "Boastful threatening" , "Vaunted courage" .)