Rotating shaft (7)
I believe the answer is:
spindle
'rotating shaft' is the definition.
(spindle is a kind of rotating shaft)
This is all the clue.
(Other definitions for spindle that I've seen before include "Device for winding thread" , "Rod serving as an axis of rotation" , "Rod on which something turns" , "Rod used in spinning" , "This could be with knobs on" .)