The unbelievable part? (3)
I believe the answer is:
lie
'the unbelievable part?' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Maybe there's an association between them I don't understand?
'unbelievable part?' is the wordplay.
'part?' indicates a hidden word.
'LIE' is hidden in the letters of 'unbelievable'.
Can you help me to learn more?
(Other definitions for lie that I've seen before include "Whopper" , "A white one is considered harmless" , "Commit perjury" , "Be prostrate" , "Recline - untruth" .)