Possible Clues:

• Ancient underground tunnel
• About a hundred in burial place in vault
• Underground alcoved tunnel for burying the dead
• Subterranean burial place
• About a hundred in burial place in underground vault
• Pet grooming implement found outside a burial chamber
• Half of falling water has to go through a series of tunnels
• Get a firm doctor under your pet under the ground
• A thorough search following Tom in the crypt
• Get down to it to give pussy this for a groom