Auden poem: close to the end when master interrupts (5,4)
I believe the answer is:
night mail
'auden poem' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.
'close to the end when master interrupts' is the wordplay.
'close to' becomes 'nigh' (I've seen this in another clue).
'the end when' becomes 'til' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'master' becomes 'ma' (Master of Arts).
'interrupts' means one lot of letters goes inside another.
'til' going around 'ma' is 'tmail'.
'nigh'+'tmail'='NIGHT MAIL'
Can you help me to learn more?
(Other definitions for night mail that I've seen before include "well-known poem" , "Subject of Auden poem" .)