Announce new metal group (10)
I believe the answer is:
promulgate
'announce' is the definition.
(I know that promulgate is a type of announce)
'new metal group' is the wordplay.
'new' is an anagram indicator.
'metal'+'group'='metalgroup'
'metalgroup' anagrammed gives 'PROMULGATE'.
(Other definitions for promulgate that I've seen before include "Publish, put about" , "Make public" , "Broadcast" , "Advertise" .)