Balcony (7)
(Other definitions for parapet that I've seen before include "protection from fire" , "keep overlooking this?" , "Wall edging a roof or bridge" , "Wall, a low sort" , "Low wall along the edge of a balcony" .)
'balcony' is the definition.
(I know that gallery is a type of balcony)
This is all the clue.
(Other definitions for gallery that I've seen before include "Covered walk" , "Group of spectators" , "Collection of art" , "Area for exhibiting works of art" , "Golf spectators" .)