Not the book or movie, I already did that.
D&D, in any version, is a game about combat and being able to protect yourself and others from damage and cause damage. The spells of the cleric and magic-users reflect this.
What isn't in most D&D books are the day-today magics, the workhorse magics or even the practical magic.
For the witch I wanted to give her her own magical niche in which to operate. I figure that most of the witches in a game world are not of the adventuring type, so they have spells that linked more to what they need to do and not cause damage per se. So charms, minor curses and hexes, but also finding things and protection.
I have also looked into the gaps of the spell lists. Quick question, what spells go into making a creature like an owlbear? Where would you start? Well I have those spells too. Good low level witches will often act as a mid-wife in many villages, so the same spells that are used to protect the mother and newborn (and to ensure conception to begin with) can be altered to other means. Not always evil or insane means. In my game "Batlings" are a magical crossbreed that are not aberrations, but a new race born of magic.
I have given long thought to how each spell can be used in an adventure like setting. I have also thought about how each spell would be useful to that NPC witch, either the local herb woman or the evil Witch Queen that the PCs must defeat. There are still going to be some though that are useful to the witch, but maybe not a useful in combat situations.
I am still following Tom Moldvay's advice on witches. Even though this is a "retro era inspired" game, modern audiences have expectations. Years of Charmed, Buffy, and Harry Potter have given us new ideas on witches. I want to retain that late 70s, early 80s feel, but sell it to a post 2010 audience.
Whatever your expectations are I hope you enjoy.