firstly try to “cut out” the sections of the mesh that will have the cloth sim. this will make the cloth simulation much faster.
secondly , select the verts ONLY on the edges of the “membrane” (the parts attached to the rest of the wing.) and turn them into a group… name this group “pinning” or something.
use this as the pinning group in the cloth physics panel, and ensure the pinning weight is 1.
if this is sufficient, you should be done.
However if there will be collisions between the wing and the rest of the creature… you will need to ensure the creatures mesh has correct collision settings… this will stop the flappy bit from intersecting the rest of the creatures mesh.
there are similar things to use in soft-body physics. only its refereed to as “goal group” rather than “pinning group”
and the softbody deformation works slightly differently…
after you have pinned your cloth mesh you can tweak the settings to get the right look and feel of the simulation…
try the default “leather” as a start , and adjust to your requirements.