Long-distance supplier of Meals on Wheels? (10,3)
I believe the answer is:
restaurant car
'long-distance supplier' is the definition.
The definition suggests a singular noun which matches the answer.
'meals on wheels?' is the wordplay.
I cannot really see how this works, but
'on' could be 're' ('on' can be mean 'with reference to') and 're' is located in the answer.
'wheels?' could be 'car' (car wheel is a kind of wheel) and 'car' is located in the answer.
This explanation may well be incorrect...
'of' acts as a link.
(Other definitions for restaurant car that I've seen before include "Railway diner" , "Train eating place" , "Train's diner" , "Train's eating place" , "Where Poirot scoffed" .)