Delayed start for hostilities — bad weather combination brings ceasefire (9)
I believe the answer is:
armistice
'ceasefire' is the definition.
(I've seen this before)
'delayed start for hostilities bad weather combination' is the wordplay.
'delayed start for' means to remove the first letter (the word begins at its second letter).
'hostilities' becomes 'war' (I've seen this before).
'bad weather' becomes 'mist'.
'combination' becomes 'ice' (I can't explain this - if you can you should give a lot more credence to this answer).
'war' with its first letter taken away is 'ar'.
'ar'+'mist'+'ice'='ARMISTICE'
'brings' acts as a link.
(Other definitions for armistice that I've seen before include "harbinger of peace?" , "Cease-fire in order to conduct talks" , "let-up from war" , "End of hostilities" , "Truce" .)