A French-built anti-ship missile (6)
I believe the answer is:
exocet
'a french-built anti-ship missile' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for exocet that I've seen before include "Subsonic, low-altitude missile" , "Weapon" , "Short-range guided missile" , "Tactical missile" , "French missile used by Argentina in the Falklands War" .)