They roared with wind by two but were swinging by three! (8)
I believe the answer is:
twenties
'they roared' is the definition.
(the 1920s were the 'roaring twenties')
I can't explain the remainder of the clue.
(Other definitions for twenties that I've seen before include "First adult years" , "Scores" , "decade of frivolity" , "ten years" , "what lies ahead for 27 [TEENAGER]?" .)