Bitter about being thrown into truck (6)
I believe the answer is:
arctic
'bitter' is the definition.
(I've seen this before)
'about being thrown into truck' is the wordplay.
'about' becomes 'c' (abbreviation for circa).
'being thrown into' indicates putting letters inside.
'truck' becomes 'artic' (short for articulated lorry).
'c' put into 'artic' is 'ARCTIC'.
(Other definitions for arctic that I've seen before include "Of area round N. Pole" , "Northernmost regions" , "Extremely cold" , "Region around the North Pole" , "-- Circle; -- fox" .)