Can I play Disposal Order in response to Fizz in order to recycle the spell they were targeting?

Yes, you can play Disposal Order in response to Fizz, Trickster's triggered ability to recycle the target spell.

However, it is important to understand the timing and the outcome of this interaction:

The Interaction Breakdown

1. Playing Fizz: You play Fizz, Trickster. Fizz enters the chain as a pending item, finalizes, and enters the board.
2. WYPM Trigger: Once Fizz is in play, his "When you play me" (WYPM) ability triggers and is placed on the chain. At this moment, your opponent must choose and declare the target spell in their trash (RiftJudge FAQ #10020, #9214).
3. Response: You can now respond to that ability with Disposal Order.
4. Disposal Order Resolution: Your Disposal Order resolves. You choose the spell your opponent targeted and force them to recycle it.
5. Fizz Ability Resolution: When the chain resolves down to Fizz's ability, it attempts to execute its instruction to play that specific spell. Because that spell is no longer in the trash (it has been recycled into the deck), the target is now unavailable. Per Rule 359.3.e.7, because the target is unavailable, Fizz's instruction to play it is ignored.

Summary

• You cannot "make" them recycle the spell instead of casting it in a way that allows them to still cast it.
• By using Disposal Order to recycle the targeted spell before Fizz's ability resolves, you cause the ability to fail to execute, meaning the spell will not be played at all.

This is my interpretation based on the mechanics of triggered abilities, targeting timing, and illegal instructions as defined in the retrieved RiftJudge FAQs and Core Rules. No official FAQ contradicts this.