Most of its leaves will have gone by the end of autumn (8)
I believe the answer is:
calendar
'autumn' is the definition.
The answer and definition can be both related to time as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'most of its leaves will have gone by the end' is the wordplay.
I cannot quite understand how this works, but
'the end' could be 'end' and 'end' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'of' is the link.
Can you help me to learn more?
(Other definitions for calendar that I've seen before include "Table of months and days" , "list of appointments" , "Year chart" , "Tabular array of days" , "Chart showing months and days" .)