How to limit users who can update a text widget

We are using the Text widget to display the daily course conditions at a golf club. This needs to be updated frequently through the admin facility as conditions change.

I would like to give access to just this widget to a range of staff members so they can make the updates but I do not want them to be able to access any other widgets or have access to any of the other back-end admin features.

Is there some way to control access at this level?