Single person annoyed about missing date (6)
I believe the answer is:
anyone
'annoyed about missing date' is the definition.
I don't know anything about this answer so I cannot judge whether this works.
'single person' is the wordplay.
'single' becomes 'any' (I can't justify this - if you can you should believe this answer much more).
'person' becomes 'one' (I've seen this in other clues).
'any'+'one'='ANYONE'
Can you help me to learn more?
(Other definitions for anyone that I've seen before include "No particular person" , "Pick a person - doesn't matter who" , "Animal-hunting trip" , "A person in general" , "A random person" .)