Second offence will include periodical brawl (9)
I believe the answer is:
scrimmage
'brawl' is the definition.
(thesaurus)
'second offence will include periodical' is the wordplay.
'second' becomes 's' (common abbreviation).
'offence' becomes 'crime' (I've seen this before).
'will include' means one lot of letters goes inside another.
'periodical' becomes 'mag' (abbreviation for magazine).
'crime' enclosing 'mag' is 'crimmage'.
's'+'crimmage'='SCRIMMAGE'
(Other definitions for scrimmage that I've seen before include "Confused tussle" , "Disorderly struggle (on sports field)" , "Fight" , "Noisy brawl or struggle" , "messy struggle" .)