Kind of metal – party (6)
I believe the answer is:
thrash
This clue is a double definition.
'kind of metal' is the first definition.
(thrash metal is a genre of music)
'party' is the second definition.
(thrash can informally mean a party)
(Other definitions for thrash that I've seen before include "Wallop" , "Lay on - party" , "Beat heavily, perhaps with whip" , "Best" , "Beat with stick or whip" .)