Ledge (5)
'ledge' is the definition.
(synonyms)
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" .)