I have a felt Nine comp. It is a 29er with rockshox forks. The clearance is poor with a continental rubber queen tyre. Is there anything I can do to increase the clearance? (we're talking 1cm, which results in quick mud jams.)
I had a look at pics of the bike, and see the clearance is small on a 2.1 tire - Rockshox Recon and the standard 29 x 2.1 are pretty standard across many bikes (mine included) and I have not heard of a problem. The Rubber Queen is a 2.4, so I would suggest going back to a 2.1 and see if you still have a problem (maybe the bike maker does know what they are doing when they choose tire sizes). If you really want to stick to a 2.4 size, look around for a low profile tire. However, the Recon is not an AM shock - it's designed for XC, where 2.1 is the more common size used and 2.4 has little advantage.
Generally the only thing you can do it go to smaller tire or replace the shock. Smaller tire is a cheaper option.
Another option would be to stick to drier tracks. If you are getting that much mud buildup despite having a lot of fun you are likely destroying the tracks you are riding. One of the key mountain biking rules is "Tread lightly".....