Toilet water input tube getting dislodged
Unfortunately, there's no separate replacement clip nor specific hose. Of course, yours doesn't use a clip anyway and would only be included with a whole new fill valve assembly.

But, you may be able to remove the hose and take it to the Hardware, Automotive or Aquarium store for a replacement...a tiny bit thicker or fatter is ideal. Just be careful, you're dealing with that plastic garbage and aged plastic can snap.

Otherwise, with your situation. I've done very well with a 1/4" or more length of drinking straw, some fine sandpaper, tinfoil or just tape wrapped around the end of the hose. It makes for a much snugger fit for the hose to be re-secured in its hole.