A word from traveller and station wagon in America departs (8)
I believe the answer is:
postcard
'a word from traveller' is the definition.
(message from a traveller)
'station wagon in america departs' is the wordplay.
'station' becomes 'post' (synonyms).
'wagon in america' becomes 'car' (wagon can mean a type of car in US English).
'departs' becomes 'd' (common abbreviation e.g. train timetables).
'post'+'car'+'d'='POSTCARD'
'and' acts as a link.
(Other definitions for postcard that I've seen before include "Bringer of message" , "Holiday message carrier" , "Holiday missive" , "Letter without an envelope?" , "Where to write" .)