Cycling star to turn and get off seat (8)
I believe the answer is:
unsaddle
'get off seat' is the definition.
(remove from a saddle)
'cycling star to turn and' is the wordplay.
'cycling star' becomes 'saddle' (I can't justify this - if you can you should believe this answer much more).
'to' means one lot of letters go next to another (I've seen this in other clues).
'turn' becomes 'u' (a 'U-turn' is a kind of turn).
'and' becomes 'n' (common abbreviation for 'and').
'u'+'n'='un'
'saddle' after 'un' is 'UNSADDLE'.
(Other definitions for unsaddle that I've seen before include "Dislodge a horse rider from their seat" , "tend horse" , "Remove gear from horse" , "What to do after ride" , "shift from mount" .)