Magazine’s prose arranged with tact (9)
I believe the answer is:
spectator
'magazine's' is the definition.
(UK magazine The Spectator )
'prose arranged with tact' is the wordplay.
'arranged with' is an anagram indicator.
'prose' with its letters mixed up with 'tact' can make 'SPECTATOR'.
(Other definitions for spectator that I've seen before include "found on the terraces?" , "Watcher" , "Periodical" , "Looker-on" , "Eyewitness, viewer" .)