Rota (9)
'rota' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for roster that I've seen before include "Duty list for sorter" , "List showing turns of duty" , "Duty rota" , "Work rota" , "Resort (anag)" .)
(Other definitions for timetable that I've seen before include "Syllabus" , "Programme" , "Schedule of events" .)