Decorative band on a wall (6)
I believe the answer is:
frieze
'decorative band on a wall' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for frieze that I've seen before include "Painted or sculpted band running round under the ceiling" , "Decorative strip round wall" , "Rough, heavy cloth or decorative wall band" , "Band of decoration around top of wall or building" , "Sculptured band between architrave and cornice" .)