I don't know how I missed that- I'm READING through the damn DMG atm...They have a death domain in the DMG which could give you ideas. If you want to make them a cleric to represent the tribal shaman then I'd suggest just picking a wisdom score that you want them to have, at least a 14 would be my recommendation for a low-level shaman, 16+ for more powerful ones.
If you want to use the druid spells, you can just assign them, or if you want some sort of method to your madness, then grant them access to spells as a druid and then layer the death domain over top so that they have a bunch of nature themed spells with some necromancy spells available to them as well. You might even want to grant them a special ability to summon a couple of giant hyenas as a special ability of the caster.
I'm thinking along the lines of that second paragraph. In the notebook where I'm working on this project, I added the Death Domain, and it's powers to the standard Gnoll Pack Lord. This guy is NOT your typical Gnoll, and I'd like him somewhere around CR 2, maybe 3, if that's what it takes.
I dropped multi-attack and Incite Rampage, and started with the standard Gnoll's abilities. I increased his Int to 9 (average intelligence, no bonus or penalty), his Wisdom to 14 (+2), and Charisma to 12 (+1).
So, one attack action/ round; no Con bonus to HP; reduced Str and Dex bonus's to Gnoll averages, and he now has a decent, but not great Wis bonus, and a small Cha Bonus. So he's more resistant to mental effects and such.
I kept Rampage as a nasty little fallback.
Now, I'm working out how to sub in that cool summon ally ability instead of some other domain/Cleric ability.
Yeenoghu is a Demon lord, so I want to stick with that theme. Reaper and Touch of Death fall right in line, there.