So the French are not heels (5)
I believe the answer is:
soles
'not heels' is the definition.
The answer and definition can be both related to change as well as being verbs in their -s form.
Perhaps you can see an association between them that I can't see?
'so the french' is the wordplay.
'the french' becomes 'les' (plural form of 'the' in French).
'so'+'les'='SOLES'
'are' is the link.
Can you help me to learn more?
(Other definitions for soles that I've seen before include "Undersides of feet" , "Fish; bottoms of feet" , "Parts of shoes" , "Undersurfaces of feet" , "Shoe bottoms" .)