Egyptian stone structure (7)
I believe the answer is:
pyramid
'egyptian stone structure' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for pyramid that I've seen before include "Polyhedron, one face a polygon, the rest triangles with common vertex" , "Solid figure with triangular sides" , "old monument" , "Giza monument" , "Object with polygonal base and triangular sides meeting at point" .)