A second food carrier is off course (6)
I believe the answer is:
astray
'off course' is the definition.
(to be led astray is to be led off course)
'a second food carrier' is the wordplay.
'second' becomes 's' (common abbreviation).
'food carrier' becomes 'tray' (food is carried on a tray).
'a'+'s'+'tray'='ASTRAY'
'is' acts as a link.
(Other definitions for astray that I've seen before include "(Gone) in wrong direction" , "Off-course" , "wide of the mark" , "Off the right track" , "Philip -, English twentieth century poet" .)