Ledge (4)
'ledge' is the definition.
(I know that ledge can be written as shelf)
This is all the clue.
(Other definitions for shelf that I've seen before include "Horizontal surface for holding things" , "Horizontal surface to put things on" , "Flat rectangular structure in house for putting things on" , "sort of life" , "Rock ledge; underwater bank" .)
'ledge' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sill that I've seen before include "Ledge beneath a window" , "Shelf at the foot of a window" , "Mass of rock" , "Horizontal intrusion of igneous rock between sedimentaries, as in much of Hadrian's Wall" , "Window edge" .)