Sons pick greatly amusing person (6)
I believe the answer is:
scream
'greatly amusing person' 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?
'sons pick' is the wordplay.
'sons' becomes 's'.
'pick' becomes 'cream' (synonyms).
's'+'cream'='SCREAM'
Can you help me to learn more?
(Other definitions for scream that I've seen before include "Yell in fear" , "card" , "Utter a sudden loud cry" , "Sound terrified" , "Caution" .)