Car marque named after the French founder of Detroit (8)
I believe the answer is:
cadillac
'founder of detroit' is the definition.
(I've seen this in another clue)
'car marque named after the french' is the wordplay.
I cannot quite understand how this works, but
'the french' could be 'la' ('the' in French) and 'la' 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 cadillac that I've seen before include "Make acid call to car company" , "American brand of luxury car" , "Luxury US automobile" , "Car maker" , "Luxury US car" .)