Sadaka, like many traps, don't act like normal ice, but instead function as a weird kind of operation that fires when the runner runs on it. Since it doesn't end the run, it won't protect any servers, and it trashes itself so it's a one-time use, just like an operation.
The only key difference between Sadaka and an operation that has the subroutines in it's text box is consistency. Operations you play are resolved immediately, whereas Sadaka requires the runner to run on the server in order for it to trigger.
If you start to analyze the efficiency, you'll realize it's actually really darn good. This costs 2 credits, a card, and a click. First sub gives you back a card, while the second sub has you discard a card to trash a card from the runner. The first sub makes Sadaka card neutral. So where did our click, two credits, and an HQ trash go? Well, it went into trashing one of the runner's resources! Suppose you trash a daily casts with 6 credits on it using Sadaka. Then you've essentially traded a card and a click for 4 credits. That's the same efficiency as hedge fund! (Of course, this is assuming a few things like runner credits/clicks/cards are of equal value to your own, which probably isn't entirely true). Trash anything larger like The Artist, Professional Contacts, Red Team, Liberated Account, or Assimilator and you're coming out on top by a ridiculous margin. While this doesn't seem that likely, keep in mind that you get to choose which resource to trash, and the runner will likely build up quite a few resources (Assuming they aren't going tag me). All this doesn't consider the additional value you get from this being a facedown ice that has bluffing value, and might eat the expose of a Deuces Wild, something Hedge Fund never could've done.
I think the best way to think about Sadaka The efficiency of this card is nuts, it just needs you to be able to get the runner to actually run the ice decently soon. In a sense, it's like you are investing a card and a click to give you higher returns, but significantly later. It's like if hedge fund read "Net 6 credits after 2 turns." I'm not sure if that's better than the current hedge fund, since it means you recover slower and there is a window of weakness where you've invested without return. If you think you can get the runner to run Sadaka consistently and soon, this could be a valuable include - albeit as an funky value operation, not a piece of ice. Something like Jinteki: Restoring Humanity could be a good home for this card, allowing you to put it on archives which will likely be ran.