Token of sincerity - and nervousness (9)
I believe the answer is:
handshake
This clue could be a double definition.
'token of sincerity' is the first 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?
'nervousness' is the second definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.
'and' is the link.
Can you help me to learn more?
(Other definitions for handshake that I've seen before include "A link" , "Physical greeting" , "Gesture of greeting or of agreeing a deal" , "Conventional greeting of manual kind" , "acknowledgment" .)