Mind (a child) (4-3)
(Other definitions for baby-sit that I've seen before include "Tend" , "Mind small children while parents have a night out" , "Take charge to allow parents to go out" , "Look after children temporarily" , "Relieve parents" .)
(Other definitions for babysit that I've seen before include "Look after children temporarily" , "Mind" , "Supervise in loco parentis" , "Take charge to allow parents to go out" , "Tend to kid" .)