"Heavy" music genre (5)
I believe the answer is:
metal
'heavy music genre' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for metal that I've seen before include "Gold or silver in heraldry" , "Copper or silver, say" , "Musically it can be heavy" , "Eg, titanium" , "Broken stone used in road-making" .)