Crossword puzzle clue "some idea"

Some idea

Lame last-minute Halloween costume idea #3: slap on a sheet, borrow some Birkenstocks and suddenly you're an ___

Some film credits, and the idea behind the eight theme answers in this puzzle

Does some job or other on a movie set (full disclosure, I have no idea what this actually means, but I think it involves tape)

Most vital part of some idea

Provides some idea of an object's size?

One who definitely loves doing all the fun youth drugs. Say, any idea where I could buy some of those? Asking because I desire to ingest them

Lame last-minute Halloween costume idea #4: tape some toothpicks to a negligee and bam, you're a ___