Concerned with a Conservative’s regular turns (9)
I believe the answer is:
repertory
'regular turns' is the definition.
(repertory theatre, regular turns on stage)
'concerned with a conservative's' is the wordplay.
'concerned with' becomes 're' (re can mean regarding, concerning).
'a' becomes 'per' (eg 'one a day' means 'one per day').
'conservative' becomes 'tory' (informal term for a Conservative Party member).
're'+'per'+'tory'='REPERTORY'
(Other definitions for repertory that I've seen before include "Collection" , "performance" , "Type of theatre" , "Playhouse performing a regular stock of works" .)