Mafioso who's alone, hiding headgear (2,6)
I believe the answer is:
al capone
'mafioso' is the definition.
I know nothing about this answer so I can't judge whether this works.
'alone hiding headgear' is the wordplay.
'hiding' indicates putting letters inside.
'headgear' becomes 'cap' (cap is a kind of headgear).
'alone' placed around 'cap' is 'AL CAPONE'.
'who's' acts as a link.
Can you help me to learn more?
(Other definitions for al capone that I've seen before include "criminal" , "Chicago gangster known as Scarface" , "Hood" , "Notorious Chicago gangster called Scarface" , "Notorious gangster, d. 1947" .)