Party held in contravention (4)
I believe the answer is:
rave
'party' is the definition.
(type of dance party)
'held in contravention' is the wordplay.
'held in' indicates the answer is hidden within the clue.
'RAVE' is hidden in the letters of 'contravention'.
(Other definitions for rave that I've seen before include "Modern youth dance - sounds hysterical" , "Pop dance party" , "Rant about an all-night dance party?" , "Rapturous" , "Wild party; go mad" .)