Clever commercial nonsense that takes one in (6)
I believe the answer is:
adroit
'clever' is the definition.
(I've seen this before)
'commercial nonsense that takes one in' is the wordplay.
'commercial' becomes 'ad'.
'nonsense' becomes 'rot' (I've seen this before).
'that takes' says to put letters next to each other.
'one' becomes 'i' (Roman numeral).
'in' means one lot of letters goes inside another.
'ad'+'rot'='adrot'
'adrot' enclosing 'i' is 'ADROIT'.
(Other definitions for adroit that I've seen before include "Skilful or ingenious" , "To raid (anag)" , "Canny" , "Skilled" , "Clever - crafty" .)