Very cold child originally found in lorry (6)
I believe the answer is:
arctic
'very cold' is the definition.
(with arctic temperatures)
'child originally found in lorry' is the wordplay.
'originally' says to take the initial letters.
'found in' is an insertion indicator.
'lorry' becomes 'artic' (articulated lorry is a semi-trailer truck).
The initial letter of 'child' is 'c'.
'c' going inside 'artic' is 'ARCTIC'.
(Other definitions for arctic that I've seen before include "icy conditions" , "Bitter" , "Freezing cold like North Pole" , "Polar region" , "Poplar region" .)