It's a two-seater, as the saying goes! (7,3)
I believe the answer is:
company car
'two-seater as the saying goes' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.
'it's a' is the wordplay.
I cannot really see how this works, but
'a' could be 'an' and 'an' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for company car that I've seen before include "Vehicle provided by one's employer" , "Wheels on firm" .)