This childish fight can escalate rapidly (8)
I believe the answer is:
snowball
I believe this is a double definition.
'this childish fight' is the first definition.
(snowball fight)
'escalate rapidly' is the second definition.
(to snowball is to escalate or accumulate quickly)
'can' acts as a link.
(Other definitions for snowball that I've seen before include "Quickly grow" , "A mixture of drugs" , "kind of bush with white flowers" , "Cold missile - advocaat and lemonade cocktail" , "Missile thrown by children in hard winter" .)