Hi Jimmliko,
Have you tried removing the widget from the dashboard and then dragging it out again? If not, try that. If the problem persists, drag another instance of the clock widget out onto the dashboard, set it for another location and see if that clock shows the same symptoms.
If the problem persists, remove all instances of the world clock from your dashboard. Next, launch Activity Monitor and look at the list of running processes. Verify that "World Clock DashboardClient" does not appear on the list of running processes. If it does, use Activity Monitor to quit it.
Then delete the preference file for the widget. To do so, go to your home folder and choose 'Library.' Then choose 'Preferences' and scroll down to the bottom. You'll see a file called:
"widget-com.apple.widget.worldclock.plist"
Delete it. Now, open Dashboard, drag a new clock onto it and verify that the problem is solved.