Fast warships (5)
I believe the answer is:
fleet
'fast' is the definition.
(similar in meaning)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for fleet that I've seen before include "task force" , "Swift like naval force" , "ships, lots of them" , "group of taxis, for example" , "Swift - London street" .)