Reversible hub? (5)
I believe the answer is:
rotor
This might be a double definition.
'reversible' is the first definition.
'hub?' is the second definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps there's a link between them I don't understand?
Can you help me to learn more?
(Other definitions for rotor that I've seen before include "Turning part of a mechanism" , "Turner" , "I go round" , "... and another" , "Revolver" .)