Here on-line courses, Polish and so on, are cut (6,3)
I believe the answer is:
buffet car
'here on-line courses' is the definition.
(a buffet car offers courses on a train line)
'polish and so on are cut' is the wordplay.
'polish' becomes 'buff' (buffing is a kind of polishing).
'and so on' becomes 'etc' (synonyms).
'cut' means to remove the last letter.
'are' with its final letter taken away is 'ar'.
'buff'+'etc'+'ar'='BUFFET CAR'
(Other definitions for buffet car that I've seen before include "where fast food is obtained?" , "moving place to snack" , "catering venue" , "dining carriage" .)