Take offence, left in second-class transport (6)
I believe the answer is:
bridle
'take offence' is the definition.
(I've seen this before)
'left in second-class transport' is the wordplay.
'left' becomes 'l' (common abbreviation).
'in' is an insertion indicator.
'second class' becomes 'b'.
'transport' becomes 'ride' (I am not sure about this - if you are sure you should believe this answer much more).
'b'+'ride'='bride'
'l' inserted within 'bride' is 'BRIDLE'.
Can you help me to learn more?
(Other definitions for bridle that I've seen before include "Show indignation" , "Part of horse's harness that goes on its head" , "Headgear used to control a horse" , "Rein" , "Take offence" .)