Sail about to find a missile (6)
I believe the answer is:
cruise
'sail' is the definition.
(cruising is a kind of sailing)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for cruise that I've seen before include "Sail smoothly" , "Sail on a ship" , "Holiday at sea" , "Sea trip" , "Holiday on liner" .)