Crossword Puzzle Oratory opening?

Clue: Oratory opening?

Opening on a stage floor (TRAPDOOR with 8 letters)
Thermal opening? (ISO with 3 letters)
Opening time (NINE with 4 letters)
Opening line? (ABCDE with 5 letters)
Round openings in domes (OCULI with 5 letters)
Dermatology opening (PORE with 4 letters)
Opening bit (ANTE with 4 letters)
Opening to an underground network (GOPHERHOLE with 10 letters)
Opening of a 1957 hit song (DAYO with 4 letters)
___ Defense (chess opening named after an Eastern European) (SLAV with 4 letters)