Fake identify of papa upsets Anne and myself (3,4)
I believe the answer is:
pen name
'fake' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'of papa upsets anne and myself' is the wordplay.
I cannot really understand how this works, but
'papa' could be 'p' (phonetic alphabet: alpha, bravo, charlie etc.) and 'p' is present in the answer.
an anagram of 'anne' is 'enna' which is within the answer.
'myself' could be 'me' and 'me' is found in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
'identify' acts as a link.
Can you help me to learn more?
(Other definitions for pen name that I've seen before include "Writer's pseudonym" , "Nom-de-plume" , "Nom de plume" , "such as Mark Twain" , "Author's pseudonym" .)