Underground cemetery (9)
'underground cemetery' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for catacomb that I've seen before include "crypt" , "Underground tunnel for bodies" , "Burial-place" , "tunnel for burial" , "Professional kneader" .)
(Other definitions for catacombs that I've seen before include "Underground cemeteries constructed by the ancient Romans" , "Underground tombs" , "Underground burial chambers" , "burial place" , "Vaults" .)