Characters predominantly seen working in milk float (4)
I believe the answer is:
swim
'float' is the definition.
('swim' can be a synonym of 'float')
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for swim that I've seen before include "Do the butterfly, perhaps?" , "Be immersed" , "Move through the water - be dizzy" , "Go for a dip" , "What to do in a pool" .)