Possible Clues:

• Mother wraps good, hot filling in crust
• 47 Across outflow
• Semi-fluid material within the earth's crust
• Rock periodical graduate follows
• Igneous rock, in time
• What igneous rock used to be
• Mum eats good bit of crust
• Igneous rock maker
• Money advanced to hold shareholders' gathering is factor in outburst
• Igneous rock former