Month before border chaos (6)
I believe the answer is:
mayhem
'chaos' is the definition.
(I've seen this before)
'month before border' is the wordplay.
'month' becomes 'may' (May is an example).
'before' means one lot of letters go next to another.
'border' becomes 'hem' (I've seen this before).
'may'+'hem'='MAYHEM'
(Other definitions for mayhem that I've seen before include "Total chaos" , "Big trouble!" , "Violent damage, chaos" , "Havoc, violent disturbance" , "Violent or damaging action, a crime" .)