I don't think they make it into a powder. They put chunks out for the birds, sometimes mixed with peanut butter. Some wrap it around a roast to keep it from drying out. My grandmother used it as an ingredient for her fabulous English mince meat pie. Boy, do I miss that!
After all the talk about suet, let me relate only to your play.
I believe you didn't allow time to develop your characters. What was their relationship to the other? What was Edith's motivation for killing Jack? You should show us an example, let them play it out. You could expand upon it. Again my major criticism is the lack of character development. The story is just fine with me. To paraphrase mac, don't telegraph where it is going. Once the audience knows, it's over. Tease you audience and pull them into the mystery. You can do this. Please think about this and what everybody has said and give us a rewritten version. That is afterall what a critique is geared toward. Relax into your play and take as long as you need. If you must have a one-pager, then go back and carefully edit any extraneous dialogue, which is something every playwright must always do anyway.
I really want to see this play developed. You have an excitement that shines through. Don't just leave it and move on to another. That will not help you grow as a playwright.
Also, change how she talks about suet to something like "special suet recipe" and/or "the secret is what I mix in with the suet" which is, in fact, the truth. Maybe it is humans, the postman or a door to door salesman and now it is Jack she will mix in with the suet that birds find so attractive.
I'm looking forward to your next draft. We all are. Thank you for sharing this with us.