Monolith (7)
I believe the answer is:
obelisk
'monolith' is the definition.
(thesaurus)
This is the entire clue.
(Other definitions for obelisk that I've seen before include "Stone "needle"" , "Tapering square stone monument" , "Square stone column that tapers" , "Tapering, rectangular stone column" , "Cleopatra's Needle, perhaps?" .)