Open-sided gallery (6)
I believe the answer is:
loggia
'open-sided gallery' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for loggia that I've seen before include "Structure similar to verandah" , "Open-sided gallery or arcade" , "Covered arcaded gallery" , "Open-sided gallery for viewing" , "Covered arcade, Italian-style" .)