If you really want the job, mention that you do community volunteer work and that you want to make sure that other worthy causes aren't affected -- so you want

If you really want the job, mention that you do community volunteer work and that you want to make sure that other worthy causes aren't affected -- so you want to send the contract to your lawyer, and have it hashed out between lawyers. Then make sure your lawyer really knows what your goals are so that they can get the wording changed. Specifically, I'd accept wording that included "excludes personal project work done 100% outside of a work context, unless such work is related to a direct work assignment". But a lawyer would have to point out any loopholes in that wording.