Rare/archaic but attested verb meaning to guard or supervise.
Definitions
To supervise, guard, or manage in the manner of a warden. During the summer months, volunteers warden the beach to protect nesting birds.
Used attributively to modify another noun (e.g., "warden duties").
Definitions
Relating to, characteristic of, or intended for a warden. The warden badge had to be worn at all times while on duty.