Moulding between ceiling and top of a wall (7)
I believe the answer is:
cornice
'moulding between ceiling and top of a wall' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for cornice that I've seen before include "decorative feature" , "Moulding along top of building" , "Overhanging ledge of frozen snow" , "decorative part of room" , "Ornamental wall moulding" .)