Breach in border intended to be announced (12)
I believe the answer is:
infringement
'breach' is the definition.
(thesaurus)
'in border intended to be announced' is the wordplay.
'border' becomes 'fringe' (fringing is a kind of bordering).
'intended' becomes 'meant' (to mean something is to intend it).
'to be announced' shows a homophone (sound like).
'meant' is a homophone of 'ment'.
'in'+'fringe'+'ment'='INFRINGEMENT'
(Other definitions for infringement that I've seen before include "Violation of law" , "Breaking (of a law, etc)" , "Offence" , "Minor lawbreaking" .)