Leaving word as to the French boarding pass? On the contrary (5)
I believe the answer is:
adieu
'leaving word as to the french boarding' is the definition.
I can't tell whether this definition defines the answer.
'pass? on the contrary' is the wordplay.
'pass?' becomes 'die' (I've seen this before).
'on' indicates putting letters inside.
'the contrary' becomes 'au' (I can't explain this - if you can you should believe this answer much more).
'die' inserted within 'au' is 'ADIEU'.
Can you help me to learn more?
(Other definitions for adieu that I've seen before include "Farewell, adios" , "farewell message" , "Goodbye in France" , "12 Down" , "Goodbye to the French" .)