Note after journey is nonsense (5)
I believe the answer is:
tripe
'is nonsense' is the definition.
(informal term for nonsense or false information)
'note after journey' is the wordplay.
'note' becomes 'e' (musical note).
'after' is a charade indicator (letters next to each other).
'journey' becomes 'trip' (trip is a kind of journey).
'e' put after 'trip' is 'TRIPE'.
(Other definitions for tripe that I've seen before include "Pants" , "Cow's stomach lining used as food" , "Swallowed" , "Rubbish; offal" , "poor stuff" .)