English police officers rejected sergeant's last order (5)
I believe the answer is:
edict
'order' is the definition.
(I know that order can be written as edict)
'english police officers rejected sergeant's last' is the wordplay.
'english' becomes 'side' (synonyms).
'police officers' becomes 'DIs' (detective inspectors).
'rejected' indicates named letters should be taken away.
'sergeant's last' becomes 'dict' (I can't explain this - if you can you should believe this answer much more).
'side' with 'dis' removed is 'e'.
'e'+'dict'='EDICT'
Can you help me to learn more?
(Other definitions for edict that I've seen before include "Authoritative ruling" , "Declaration" , "Decree by authority" , "Legally binding proclamation" , "An official command" .)