Wheels for convenience are working: first class fit (8)
I believe the answer is:
runabout
'wheels' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.
'convenience are working first class fit' is the wordplay.
I cannot really see how this works, but
'are' could be 'a' (short for 'are', historical unit of measurement) and 'a' is found in the answer.
'fit' could be 'bout' (I've seen this in other clues) and 'bout' is located in the answer.
The remaining letters 'run' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'for' is the link.
Can you help me to learn more?
(Other definitions for runabout that I've seen before include "mini perhaps" , "small aircraft" , "little motor" , "Small A-to-B car" , "light aircraft of this type" .)