In which one's days are numbered? (8)
I believe the answer is:
calendar
'one's days are numbered?' is the definition.
(as in dates given in a calendar)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for calendar that I've seen before include "List of days etc" , "list of appointments" , "Chart of times" , "Table of the days of a year" , "List of dates of land race" .)