Mass conflict fractures defence (7)
I believe the answer is:
bulwark
'defence' is the definition.
(bulwark is a kind of defence)
'mass conflict fractures' is the wordplay.
I cannot really understand how this works, but
'conflict' could be 'war' (war is a kind of conflict) and 'war' is present in the answer.
'mass' could be 'bulk' (synonyms) and 'bulk' is found within the leftover letters.
This accounts for all the letters.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for bulwark that I've seen before include "Defensive wall" , "Fortification - side of ship above deck" , "Buttress" , "Rampart" , "defence" .)