You need a good car when in France (5)
I believe the answer is:
arras
'france' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'you need a good car when' is the wordplay.
I cannot really understand how this works, but
'a' is present in the answer.
'car' could be 'rr' (Rolls Royce) and 'rr' is found within the answer.
'when' could be 'as' (eg 'when I walked' means 'as I walked') and 'as' is found in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'in' acts as a link.
Can you help me to learn more?
(Other definitions for arras that I've seen before include "Work of art" , "Tapestry; French town" , "Polonius met his end behind one" , "Wall hanging of heavy woven fabric" , "Tapestry; WW One battle" .)