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 they can define each other.
'you need a good car when' is the wordplay.
I cannot quite see how this works, but
'a' is found in the answer.
'car' could be 'rr' (Rolls Royce) and 'rr' is located in 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 explanation may well be incorrect...
'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" .)