Curved structure in Star Chamber (4)
I believe the answer is:
arch
'curved structure' is the definition.
(I've seen this before)
'in star chamber' is the wordplay.
'in' indicates the answer is hidden within the clue.
'ARCH' is hidden in the letters of 'star chamber'.
(Other definitions for arch that I've seen before include "Playfully superior" , "Curve of the foot" , "Cunning; bridge" , "Clever" , "Consummate" .)