Big picture? (5)
'big picture?' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for mural that I've seen before include "Drawing on a wall" , "Large wall painting" , "Painting on a wall, fresco" , "Wall decoration" , "Wall design" .)
(Other definitions for gestalt that I've seen before include "whole of psychology" , "Organised whole, more than the sum of its parts" , "Pattern perceived as whole" , "establish a pattern" .)