Fabric Spray?
 

Is there a fabric spray that can be used to attach minky backing to a t-shirt top?

It sort of depends on how permanent you want it. For costuming or articles that won't be washed a lot, I think you would be pretty good. I am mostly familiar with quilting sprays that dissipate. Not sure how well it would work if you are trying to permanently line the t-shirt.

Just look for the term "permanent" instead of "temporary". Some of the adhesives are designed for different uses (like attaching trims/gems to fabric) and some may work better for what you want. Here a couple choices --
https://www.aleenes.com/aleenes-fabr...hesive-4-fl-oz
https://www.gorillatough.com/product...a-fabric-glue/

Many brands -- Elmer's makes a spray and maybe regular glue will work too.

You would need to check to see if it discolors/can be seen through the minkee, I would guess that most would show through the tshirt.

I should have been clearer. I need a spray that will eventually wash out. It’s for a quilt.

Tracy at The Sewing Channel on UTube does minky backings on a lot of her projects and also uses different techniques. Maybe worth snooping around to see if there are any you'd want to try. One of them might have been a spray. I don't remember for sure; I've been binge watching too much lately.