Called round on policeman's orders (7)
I believe the answer is:
demands
'orders' is the definition.
(order can mean a demand or instruction)
'called round on policeman's' is the wordplay.
'called' becomes 'named' (synonyms).
'round' says the letters should be written backwards.
'on' is a charade indicator (letters next to each other).
'policeman' becomes 'ds' (abbreviation for Detective Sergeant).
'named' in reverse letter order is 'deman'.
'deman'+'ds'='DEMANDS'
(Other definitions for demands that I've seen before include "Insists upon" , "Requires" , "Insistent requests" , "Orders" , "Asks peremptorily" .)