Sheet is one of these (7)
I believe the answer is:
anagram
'sheet' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Perhaps there's a link between them I don't understand?
'one of these' is the wordplay.
I cannot really understand how this works, but
'one' could be 'an' (an apple is one apple) and 'an' is found within the answer.
This explanation may well be incorrect...
'is' is the link.
Can you help me to learn more?
(Other definitions for anagram that I've seen before include "reordering" , "Jumble of letters" , ""Supersonic"of "percussion", for example?" , "New arrangement" , "Word arranging the letters of another" .)