If you are comfortable with a heelhook on the right (big hold), you will be able to reach the crimp rather statically. Otherwise just go for it :) Once you've done the 6c definitely try the 7a version to the left, you might even find it easier!
Rain sucks, but broken holds suck even more. Remember, never climb on wet rock in Fontainebleau.
The sandstone becomes brittle, and pulling on it will ruin classic problems. Drying it doesn't help, because it's still wet and weak inside.
All you can do is wait for better conditions.