Security clearance does not always prove integrity. It simply proves that you have that particular clearance, whatever it may be (I've had secret clearance for more than 4 years now).
No, it has nothing to do with meeting the experience requirements per ISC2. Think of it this way; some janitors at certain military and government installations have clearance, but that in no way qualifies them to sit for the CISSP. I guess the real question could be, what's the job function of the job that might require you to get the clearance. It might very well be a good step in the right direction for gaining the needed experience. Good luck.
CISSP, MCT, MCSE2K/2K3, MCSA, CEH, Security+, Network+, CTT+, A+