He makes nothing but new cars (5)
I believe the answer is:
oscar
'he' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
Maybe there's a link between them I don't understand?
'nothing but new cars' is the wordplay.
I cannot quite understand how this works, but
'nothing' could be 'o' (O resembles 0) and 'o' is found in the answer.
an anagram of 'cars' is 'scar' which is present in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'makes' is the link.
Can you help me to learn more?
(Other definitions for oscar that I've seen before include "Movie award, popularly called" , "Hollywood statuette given as annual award" , "Boy" , "Develop again" , "US film award" .)