For example, that's what's seen in some poetry (3,5)
I believe the answer is:
eye rhyme
'for example' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
'what's seen in some poetry' is the wordplay.
'what's seen in some' becomes 'eye' (I can't explain this - if you can you should believe this answer much more).
'poetry' becomes 'rhyme' (rhyme is a type of poetry).
'eye'+'rhyme'='EYE-RHYME'
'that's' is the link.
Can you help me to learn more?
(Other definitions for eye rhyme that I've seen before include "shy?" , "Keats and Yeats, for example" , "Similarity in spelling but not sound as in love and move" , "Love and move eg" , "Maid said, for example" .)