A bunch of taxis moving swiftly (5)
I believe the answer is:
fleet
'a bunch' is the definition.
(thesaurus)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for fleet that I've seen before include "good turn of speed" , "Navy - quick" , "Swift like naval force" , "ships, lots of them" , "Fast and nimble" .)