Rocking on vocal, one issues hot stuff (7)
I believe the answer is:
volcano
'one issues hot stuff' is the definition.
(source of hot lava)
'rocking on vocal' is the wordplay.
'rocking' indicates an anagram.
'on'+'vocal'='onvocal'
'onvocal' is an anagram of 'VOLCANO'.
(Other definitions for volcano that I've seen before include "kind of mountain" , "Mountain (could be a heavy smoker!)" , "Dormant or active mountain" , "E.g. Vesuvius, Etna" , "Exploding mountain" .)