Journey with the French trio (6)
I believe the answer is:
triple
'trio' is the definition.
(I know that trio can be written as triple)
'journey with the french' is the wordplay.
'journey' becomes 'trip' (trip is a kind of journey).
'with' is a charade indicator (letters next to each other).
'the french' becomes 'le' ('the' in French).
'trip'+'le'='TRIPLE'
(Other definitions for triple that I've seen before include "Multiply by three" , "Threefold, treble" , "In three parts" , "involving several parties" , "make score sixty?" .)