If you read the fine print on soundclick. They Assume you own the license if you post a cover song. If you do not, And someone complains. Soundclick will delete your file and wash there hands of you. Then you will be subject to legal action from the offended parties. You can however buy a mechanical license to most cover songs and post away. I'm not sure of the cost? Let me do a google search and see if I can find the site.
Here it is. http://www.harryfox.com/public/index.jsp