Communication by car? (5)
I believe the answer is:
cable
This clue might be a double definition.
'communication' is the first definition.
(cable is a kind of communication)
'car?' is the second definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe there's a link between them I don't understand?
'by' acts as a link.
Can you help me to learn more?
(Other definitions for cable that I've seen before include "Anchor chain; type of TV" , "Wire; message" , "Heavy chain or rope" , "Strong rope made of twisted strands of hemp, nylon or steel wire" , "Liberal Democrat" .)