Party hat shape (4)
I believe the answer is:
cone
'party hat shape' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for cone that I've seen before include "Tapering object" , "Ice-cream cornet" , "standing in middle of motorway" , "Shape, the base is a circle and the sides taper up to a point" , "Tapering shape" .)