He's so upset about a bit of credit (5)
I believe the answer is:
oscar
'bit of credit' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'he's so upset about a' is the wordplay.
'he' becomes 'rc' (I can't justify this - if you can you should give a lot more credence to this answer).
'upset' says the letters should be written backwards.
'about' is an insertion indicator.
'rc'+'so'='rcso'
'rcso' written backwards gives 'oscr'.
'oscr' placed around 'a' is 'OSCAR'.
Can you help me to learn more?
(Other definitions for oscar that I've seen before include "Cinema award" , "Award by the Academy of Motion Picture Arts and Sciences" , "Film acting award" , "Wildean film award?" , "heard on the radio after November" .)