Sister reported an absence (4)
I believe the answer is:
none
'absence' is the definition.
Both the definition and answer are singular nouns.
Perhaps they are linked in a way I don't understand?
'sister reported' is the wordplay.
'sister' becomes 'nun' (nuns are referred to as sister).
'reported' shows a homophone (sound like).
'nun' is a homophone of 'NONE'.
'an' acts as a link.
Can you help me to learn more?
(Other definitions for none that I've seen before include "Pet menu chez Hubbard" , "Not even one" , "hour of prayer" , "office" , "Not one thing" .)