Policeman’s instruction creating chaos (8)
I believe the answer is:
disorder
'chaos' is the definition.
(I know that chaos can be written as disorder)
'policeman's instruction' is the wordplay.
'policeman's' becomes 'di's' (detective inspector).
'instruction' becomes 'order' (an order to do something).
'dis'+'order'='DISORDER'
'creating' is the link.
(Other definitions for disorder that I've seen before include "Chaos" , "Although it's only a minor ailment" , "Indiscipline" , "Commotion" , "Muddle" .)