A stage constructed of stones (6)
I believe the answer is:
agates
'stones' is the definition.
(I've seen this before)
'a stage constructed' is the wordplay.
'constructed' indicates anagramming the letters.
'stage' with letters rearranged gives 'gates'.
'a'+'gates'='AGATES'
'of' acts as a link.
(Other definitions for agates that I've seen before include "marbles" , "Hard stones with concentric bands of colour" , "Chalcedonies" , "Banded semiprecious stones" , "Stones to be found in a stage" .)