Detectives' line-up for breach of the peace (8)
I believe the answer is:
disorder
'breach of the peace' is the definition.
(I've seen this before)
'detectives' line-up' is the wordplay.
'detectives'' becomes 'dis' (Detective Inspectors, DIs).
'line up' becomes 'order' (I can't explain this - if you can you should believe this answer much more).
'dis'+'order'='DISORDER'
'for' acts as a link.
Can you help me to learn more?
(Other definitions for disorder that I've seen before include "Muddle" , "Riders do (anag)" , "breach of the peace" , "Do driers create untidiness?" , "Confused state" .)