Vital musical instrument? (5)
I believe the answer is:
organ
This could be a double definition.
'vital musical' is the first definition.
The answer and definition can be both related to communication as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'instrument?' is the second definition.
(organ is a kind of instrument)
Can you help me to learn more?
(Other definitions for organ that I've seen before include "Biological functionary" , "Perhaps one that's stopped" , "Wind instrument found in the body." , "ear maybe" , "Medium; body part" .)