Gangster on his own without detonator (2,6)
I believe the answer is:
al capone
'gangster' is the definition.
(I've seen this before)
'on his own without detonator' is the wordplay.
'on his own' becomes 'alone' (I am not sure about this - if you are sure you should believe this answer much more).
'without' means one lot of letters goes inside another ('without' can be similar in meaning to 'outside').
'detonator' becomes 'cap' (synonyms).
'alone' going around 'cap' is 'AL CAPONE'.
Can you help me to learn more?
(Other definitions for al capone that I've seen before include "US gangster in Chicago, arrested for tax evasion" , "Chicago gangster known as Scarface" , "Notorious gangster, d. 1947" , "Notorious Chicago gangster arrested for tax evasion" , "Notorious Chicago gangster called Scarface" .)