Note soldiers breaking welcome pact (9)
I believe the answer is:
agreement
'pact' is the definition.
(I've seen this in another clue)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for agreement that I've seen before include "legal contract maybe" , "State of being consistent" , "concert" , "Conformity" , "Pact" .)