Sneakiness evident if loading lorry with last of merchandise (8)
I believe the answer is:
artifice
'sneakiness' is the definition.
(thesaurus)
'if loading lorry with last of merchandise' is the wordplay.
'loading' is an insertion indicator (some letters are loaded into others).
'lorry' becomes 'artic' (short for 'articulated lorry').
'with' says to put letters next to each other.
'last of' suggests the final letters.
The last letter of 'merchandise' is 'e'.
'if' going within 'artic' is 'artific'.
'artific'+'e'='ARTIFICE'
'evident' is the link.
(Other definitions for artifice that I've seen before include "Race it if (anag) - cunning" , "Clever contrivance" , "Crafty deception or stratagem" , "a lot of tricks" , "Ingenious stratagem" .)