How would I set a default value for a data entry without it being on the font end add listing page?

I want to set the 'condition' data entry to default to 'used' but not allow the customer to change it.

It defaults to used correctly when the data entry field is visible but won't set if it's not on the page. Plus, if I have the 'condition' data entry visible, the 'location' data entry is not selectable.

Anybody have any ideas?