city mouse

noun2

1. •
   (figurative) A city person; someone who has city ways.
2. •
   (slang, figurative) A member of support personnel who remains at the base.

   • […] before arriving, he'd never thought it would be spent as one of the city mice. Most of the McMurdoans never ranged more than walking distance from the largest town on the entire continent. — 2021