Turning up detectives arrest men, a simple order (5)
I believe the answer is:
doric
'a simple order' is the definition.
'doric' can be an answer for 'order' (Doric order is a classical architectural order). I'm unsure of the 'a simple' bit.
'turning up detectives arrest men' is the wordplay.
'turning up' says the letters should be written in reverse.
'detectives' becomes 'CID' (abbreviation for Criminal Investigation Department).
'arrest' indicates putting letters inside.
'men' becomes 'OR' (military abbreviation for other ranks).
'cid' backwards is 'dic'.
'dic' placed around 'or' is 'DORIC'.
Can you help me to learn more?
(Other definitions for doric that I've seen before include "Type of column" , "Classical building style" , "Greek architectural order" , "Ancient dialect" , "Of the oldest and simplest form of architecture" .)