Broadcast said Royal Marines will demobilise (6)
I believe the answer is:
disarm
'demobilise' is the definition.
(thesaurus)
'broadcast said royal marines' is the wordplay.
'broadcast' is an anagram indicator.
'royal marines' becomes 'rm'.
'said' is an anagram of 'disa'.
'disa'+'rm'='DISARM'
'will' is the link.
This may not be correct. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for disarm that I've seen before include "Do away with weaponry" , "Relieve of weapons" , "Make less angry or deprive of weapons" , "Allay suspicions" , "Abandon MAD" .)