Stop defending Capone in general (9)
I believe the answer is:
prevalent
'general' is the definition.
(I've seen this before)
'stop defending capone' is the wordplay.
'stop' becomes 'prevent' (stop can mean to prevent something).
'defending' means one lot of letters goes inside another (inserted letters are defended).
'capone' becomes 'Al' (gangster Al Capone).
'prevent' placed around 'al' is 'PREVALENT'.
'in' acts as a link.
(Other definitions for prevalent that I've seen before include "powerful" , "general" , "Common" , "Widely accepted" , "Commonplace" .)