It's doubtful absorbing books will show number of patriots (6)
I believe the answer is:
anthem
'show number of patriots' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Maybe you can see an association between them that I can't see?
'it's doubtful absorbing books' is the wordplay.
'it's doubtful' becomes 'ahem' (I am not sure about this - if you are sure you should believe this answer much more).
'absorbing' indicates putting letters inside.
'books' becomes 'NT' (New Testament).
'ahem' placed around 'nt' is 'ANTHEM'.
'will' acts as a link.
Can you help me to learn more?
(Other definitions for anthem that I've seen before include "Uplifting music" , "National melody" , "Internationale?" , "Choral work" , "The man for a patriotic song" .)