Missile opening conflict in south of France (4)
I believe the answer is:
scud
'missile' is the definition.
(type of long-range missile)
'opening conflict in south of france' is the wordplay.
'opening' says to take the initial letters.
'in' indicates putting letters inside.
'south of france' becomes 'sud' (French for south).
The initial letter of 'conflict' is 'c'.
'c' placed into 'sud' is 'SCUD'.
(Other definitions for scud that I've seen before include "swift runner" , "Skim along; Russian missile" , "Sail swiftly before the wind - missile" , "Missile - move swiftly and smoothly" , "Move swiftly in the wind" .)