Clear chamber (5)
I believe the answer is:
vault
I believe this clue is a double definition.
'clear' is the first definition.
(I've seen this before)
'chamber' is the second definition.
(I know that vault is a type of burial chamber)
(Other definitions for vault that I've seen before include "Jump over a crypt? (5)" , "Leap; storage chamber" , "Strongroom or burial chamber" , "bound?" , "Underground chamber - leap" .)