Front of lorry with one secure storage unit (7)
I believe the answer is:
cabinet
'storage unit' is the definition.
(furniture item for storing things)
'front of lorry with one secure' is the wordplay.
'front of lorry' becomes 'cab' (driver's compartment on a lorry).
'with' says to put letters next to each other.
'one' becomes 'i' (Roman numeral).
'secure' becomes 'net'.
'cab'+'i'+'net'='CABINET'
(Other definitions for cabinet that I've seen before include "Piece of furniture for members of a government" , "See 18" , "Collective noun for senior ministers" , "some senior politicians" , "Item of furniture for storage or display" .)