Crossword Genius

It revolves either way (5)

Ross

I believe the answer is:

This clue is a double definition.

'it revolves' is the first definition.
(I've seen this before)

'either way' is the second definition.

(Other definitions for rotor that I've seen before include "Copter blade assembly", "Chopper blade", "Rotating part of machine", "Revolving bar", "Bit of chopper".)