Vessel shooting across the waves? (7)
I believe the answer is:
gunboat
'vessel' is the definition.
(gunboat is a kind of vessel)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for gunboat that I've seen before include "Vessel (involved in a type of diplomacy?)" , "Military vessel" , "Coastal warship" , "Not a bug (anag)" , "Naval symbol of aggression" .)