The FBI are confused by this deception (3)
I believe the answer is:
fib
'this deception' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
Maybe there's an association between them I don't understand?
'the fbi are confused' is the wordplay.
'are confused' is an anagram indicator.
'fbi' anagrammed gives 'FIB'.
'by' acts as a link.
Can you help me to learn more?
(Other definitions for fib that I've seen before include "Small lie" , "Petty falsehood" , "Story" , "minor piece of fiction" , "Trivial lie" .)