Sure, descend to the cleared altitude. If you're in radar contact, the controller can (and will in many cases) clear you to the MVA (minimum vectoring altitude). MSA is the worst case altitude.
To take it a step further, if you are cleared to an altitude, you are expected to comply "in a timely manner". You can't ignore the clearance unless he says "Pilot's discretion".
P.S. Just because you are showing glideslope indications is no guarantee that the information is usable or accurate. Normal glidslope service volume is 10 NM, but many are flight test further out. You don't know unless it's published.
Warnings about following glideslopes at distances further out than published are repeated every few years in the ALPA magazine.
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[This message has been edited by quid (edited 13 November 2000).]