Cryptic Family Reunion: Watching Your Belt (Fan-Made)

Question

Inspired by the Cryptic Family Reunion Series by Jeremy Dover

The answer to this puzzle is a list of eight 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. Aunt to gamble on the Spanish golf, supported by English work. (10)
2. Fix energy line for grandfather. (5)
3. Bill extra order to uncle. (9)
4. "Pristine" is the nickname of sister. (7)
5. Father gives a slap with nothing in it. (7)
6. Odd Atlantic merger begins thanks to a kick-start from mother. (7)
7. Nephew's weapon to power hospital. (5)
8. Brother is found inside flat-topped hill. (6)

Answer 1

These are all:

The names of the brightest stars in the constellation of Orion.

As follows:

1. Aunt to gamble on the Spanish golf, supported by English work. (10) BETELGEUSE = BET (gamble) + EL ('the' in Spanish) + G ('golf' as per NATO) + E (English) + USE (work)

2. Fix energy line for grandfather. (5) RIGEL = RIG (Fix) + EL (Energy Line)

3. Bill extra order to uncle. (9) BELLATRIX = BILLEXTRA*

4. "Pristine" is the nickname of sister. (7) MINTAKA = MINT (Pristine) + AKA (nickname='Also Known As')

5. Father gives a slap with nothing in it. (7) ALNILAM = A + LAM (slap) containing NIL (nothing)

6. Odd Atlantic merger begins thanks to a kick-start from mother. (7) ALNITAK = A_L_N_I_ + TA (thanks) + K(-ick)

7. Nephew's weapon to power hospital. (5) SAIPH = SAI (weapon) + P + H

8.Brother is found inside flat-topped hill. (6) MEISSA = MESA (flat-topped hill) containing IS

Of course, this explains the title too, since:

The constellation Orion (named after the hunter from Greek mythology due to its shape) is famous for the three bright stars which appear to form a 'belt' across its midriff.