Eight-sided shape (7)
I believe the answer is:
octagon
'eight-sided shape' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for octagon that I've seen before include "Eight-sided object" , "Geometric figure with eight sides" , "plane figure" , "An eight-sided polygon" , "Figure with 8 sides" .)