Alarm artist about methods of self-defence (7,4)
I believe the answer is:
martial arts
'methods of self-defence' is the definition.
(I've seen this before)
'alarm artist about' is the wordplay.
'about' is an anagram indicator.
'alarm'+'artist'='alarmartist'
'alarmartist' with letters rearranged gives 'MARTIAL ARTS'.
(Other definitions for martial arts that I've seen before include "Methods of self-defence" , "Eg, judo, karate" , "Weaponless self-defence sports" , "Karate, kendo etc" , "Judo, karate, etc" .)