Group of naval vessels (5)
I believe the answer is:
fleet
'group of naval vessels' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for fleet that I've seen before include "Fast-moving" , "Quick of foot" , "Swift of foot - old London jail" , "Swift; armada" , "bowler famously intercepted one once" .)