(P.S., I've never cleaned a grouse. Please elaborate. I'm not squeamish, as long as things are done humanely)
The following grouse cleaning method is not for the sensitive/squeamish, its just the normal way it's done around here.
On a grouse almost all the useable meat is in the breast.
You lay the dead bird on it's back, step on the wings close to the body, pull on the feet hard and the bird turns inside out. The wings and breast remain on the ground and the rest pulls clear attached to the legs. Snap/twist the wings off and you have 95% of the meat. The legs have about one small bite of thigh meat each, the drumsticks are full of sharp thin bones. If I have enough grouse I keep the legs for grouse/rice soup with carrots and celery (very nice).
You need to weigh a little to use this method, my 8 year old daughter tried it and was not heavy enough to hold the grouse down. I often just seperate the grouse breast/wings from the rest of the bird without laying it on the ground (especially if the ground is muddy or sandy). Tear the shin off the grouse breast and grip the breast tightly in your hand with your index finger in/under the crop, grasp the head/neck/crop in your other hand and pull hard down and away. You will be left with the breast/wings in one hand and the rest of the bird in the other.
Grouse are usually cleaned in the field before coming home, I try to do it near water so I can clean up after. The remains are left in the bush for the critters, they have to eat too (from nature, back to nature, nothing really ever goes to waste).
I apoligize if this is a little to graffic for some; Moderator if this is "over the edge" feel free to delete.
Mike