The rest of the sailors (5,5)
I believe the answer is:
shore leave
This clue could be a double definition.
'the rest' is the first 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 can't see?
'of the sailors' is the second definition.
The definition suggests a singular noun which matches the answer. I also know that 'sailors' relates to this answer.
Can you help me to learn more?
(Other definitions for shore leave that I've seen before include "Time off for sailors in port" , "rest of the crew" .)