Cycle part includes bolts occasionally (8)
I believe the answer is:
rotation
'cycle' is the definition.
(I've seen this before)
'part includes bolts occasionally' is the wordplay.
'part' becomes 'ration' (ration is a kind of part).
'includes' means one lot of letters goes inside another.
'occasionally' indicates alternate letters.
The alternate letters of 'bolts' are 'ot'.
'ration' going around 'ot' is 'ROTATION'.
(Other definitions for rotation that I've seen before include "Turn of a wheel" , "Spinning motion or cyclic changes as of crops" , "Going round" , "Act of turning" , "Recurring sequence" .)