Reportedly stabilise architectural adornment (6)
I believe the answer is:
frieze
'architectural adornment' is the definition.
(I've seen this in another clue)
'reportedly stabilise' is the wordplay.
'reportedly' indicates a 'sounds like' (homophone) clue.
'stabilise' becomes 'freeze'.
'freeze' is a homophone of 'FRIEZE'.
(Other definitions for frieze that I've seen before include "Architectural ornament" , "Sculpted or painted wall decoration" , "this band goes up the wall" , "Ornamental band around a room" , "Decorative architectural band" .)