Spitting Image covering heavy metal band's number one (10)
I believe the answer is:
ringleader
'spitting image' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'covering heavy metal band's number one' is the wordplay.
'covering' indicates putting letters inside.
'heavy metal' becomes 'lead' (lead is a heavy metal).
'band's number one' becomes 'ringer' (I can't justify this - if you can you should believe this answer much more).
'lead' put within 'ringer' is 'RINGLEADER'.
Can you help me to learn more?
(Other definitions for ringleader that I've seen before include "Chief troublemaker" , "Mastermind" , "firebrand" , "brains" , "Chief mischief maker" .)