Raid, circumventing commercial security device creating obstruction (9)
I believe the answer is:
roadblock
'obstruction' is the definition.
(I know that roadblock is a type of obstruction)
'raid circumventing commercial security device' is the wordplay.
'raid' becomes 'rob'.
'circumventing' is an insertion indicator (I've seen this in other clues).
'commercial' becomes 'ad' (abbreviation for advertisement).
'security device' becomes 'lock' (I've seen this in another clue).
'rob' going around 'ad' is 'roadb'.
'roadb'+'lock'='ROADBLOCK'
'creating' is the link.
(Other definitions for roadblock that I've seen before include "Police barricade to halt traffic" , "Barrier on way" , "Checkpoint" , "Traffic-halting barrier" , "put in place by police after fugitive" .)