How to make channel shift only inside spider print?

Question

Adobe Photoshop

Image of a T-shirt with a spider
I want to shift the channels only inside the spider print, and instead of a white background, make a transparent background so that there are no chromatic aberrations along the edges of the image separated from the background, but they are only on the spider. How can you do that?
I almost could, but I don’t understand how to remove the border on the left?

Answer 1

1) cut out the spider with a pen to get its shape.
2) cut through the shape of a spider in a T-shirt.
3) paint the spider shape black and do a channel shift.
4) remove the black color from the shifted spider, leaving the color shift.
The result will be two layers - a T-shirt with a hole in the shape of a spider and a spider outline with aberrations.

Answer 2

Please send PSD, so it's not immediately clear what method they were made with.