Cryptic Family Reunion: Down in a Hole

Question

The answer to this puzzle is a list of ten thematically related words or proper names or phrases. Each of these is clued cryptically, and the theme is to be determined. Since the definition part of a cryptic clue would give away the theme, these cryptic clues use a family member (e.g., mom, sister) to stand in for the definition part of the clue. So for example, if the theme of the puzzle were chemical elements, "Sister picking at nit" would clue "tin". I hope you enjoy!

1. Brother's desire to ascend Lhotse's peak (5)
2. Extract garlic heads for Mom (4)
3. Daughter is more confident having that guy around (8)
4. Niece's fake jewellery mimics opals under natural diamond points (9,5)
5. Husband: exclusive or no? (4)
6. Tough moving around hallway floor for grandad (6)
7. Sister displaying piece of Egyptian religious symbol first (6)
8. Montana city has voided lease with brother (7)
9. Mother's telling latest story about taking first ride from Uber after disciplining cousin (10,4)
10. Dad's iguanas going into a frenzy after eating grasshopper heart (8)

Answer 1

The theme is

Monsters from the 2nd edition of Dungeons and Dragons. Specifically, they come from the Monstrous Compendium Volumes One and Two.

As for the title... OP said there was no special meaning behind it. :P

Clue explanations:

1. GNOLL = LONG< + L_
2. LICH = _LIC H_
3. BEHOLDER = B(HE<)OLDER
4. SHAMBLING MOUND = SHAM + BLING + M_ O_ U_ N_ D_
5. XORN = XOR + N
6. OTYUGH = TO(_Y)UGH*
7. ANKHEG = ANKH + EG_
8. BULETTE = BU(L_E)TTE
9. GELATINOUS CUBE = _G + LATE< + COUSIN* + UBE(-r)
10. SAHUAGIN = IG(_H_)UANAS*