It depends on where it is, inside an inlet I will put the part in to wedge the patch in place. Outside the inlet on a curved surface that won't hold a clamp I put the patch in place and wrap the area as tightly as I can with twine. I am a bit of a bumbling gun maker so I am no stranger to patching goof-ups. A well done patch doesn't show in the finished gun.
Patches wedged into place;
I had the lower part of the lock molding break out when I put the trigger guard pin in. I had mis-drilled the first hole and missed the lug, I plugged the first hole with a toothpick and drilled another hole in the right place, when I put the pin in it followed the first hole with a plug in it and chipped out about 1" of the lock molding, the chip was still attached to the lock molding. I glued the chip back in and gave it a very tight wrap with twine.
The chipped wood went back in well, you can see the plugged first hole below the pin hole but not the crack which was extensive. After finishing the gun there is no evidence that it was ever cracked.
Finished rifle, I should have put the trigger guard pin inside the lock inlet but I was (and still am) a rookie builder and didn't know better.