The way a Frenchman is unflappable (6)
I believe the answer is:
serene
'unflappable' is the definition.
(thesaurus)
'the way a frenchman' is the wordplay.
'the way' becomes 'se' (I can't explain this - if you can you should give a lot more credence to this answer).
'a frenchman' becomes 'rene'.
'se'+'rene'='SERENE'
'is' is the link.
Can you help me to learn more?
(Other definitions for serene that I've seen before include "Calm, untroubled" , "without any trouble" , "Calm and unruffled, like a princely title." , "Tranquil, perfectly calm" , "Placid" .)