Called about Detective Sergeant's orders (7)
I believe the answer is:
demands
'orders' is the definition.
(order can mean a demand or instruction)
'called about detective sergeant's' is the wordplay.
'called' becomes 'named' ('name' can be a synonym of 'call').
'about' says the letters should be written backwards.
'detective sergeant' becomes 'DS' (abbreviation for detective sergeant).
'named' reversed gives 'deman'.
'deman'+'ds'='DEMANDS'
(Other definitions for demands that I've seen before include "Insistent requests" , "Requires" , "Requests forcefully" , "Asks peremptorily" , "Insists upon" .)