What he sells is nutritious but dear in France (7)
I believe the answer is:
butcher
'what he sells is nutritious' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'but dear in france' is the wordplay.
'dear in france' becomes 'cher' (French term of endearment).
'but'+'cher'='BUTCHER'
Can you help me to learn more?
(Other definitions for butcher that I've seen before include "more macho" , "more masculine?" , "Killer" , "Purveyor of meats" , "He cuts up and sells meat" .)