Note ascending space vehicle -- there's a rotating mechanism (8)
I believe the answer is:
sprocket
'a rotating mechanism' is the definition.
'note ascending space vehicle' is the wordplay.
'note' becomes 'ps' (PS is an example**).
'ascending' shows that the letters should be reversed in order.
'space vehicle' becomes 'rocket'.
'ps' written backwards gives 'sp'.
'sp'+'rocket'='SPROCKET'
'there's' acts as a link.
(Other definitions for sprocket that I've seen before include "Cog wheel" , "Toothed wheel that interlocks with a chain" , "Tooth on the rim of a driving wheel" , "Thin wheel with teeth driven by a chain" , "What engages with holes in cine film" .)