Shelf over a fireplace (6)
I believe the answer is:
mantel
'shelf over a fireplace' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for mantel that I've seen before include "Award-winning author" , "Shelf above a fireplace" , "Hilary?" , "Lament over fireplace structure" , "prize-winning novelist" .)