Last date's reason for not phoning? (8)
I believe the answer is:
deadline
'last' is the definition.
The definition and answer can be both related to time as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'date's reason for not phoning?' is the wordplay.
I cannot really understand how this works, but
'date' could be 'ad' (AD is an example) and 'ad' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for deadline that I've seen before include "Time for finishing" , "last possible time" , "Closing date" , "Time-limit as for journalist's copy" , "a writer may have to meet" .)