Say farewell the French way (5)
I believe the answer is:
leave
'say farewell' is the definition.
'the french way' is the wordplay.
'the french' becomes 'le'.
'way' becomes 'ave' (abbreviation for avenue, a type of 'way').
'le'+'ave'='LEAVE'
(Other definitions for leave that I've seen before include "Go - on holidays?" , "Renounce" , "ditch" , "Pull out" , "Insufficient foliage" .)