BARBARA WALKER SEVILLANO, 34, formerly of St. Petersburg, died Saturday (Oct. 20, 1984) in Clearwater, where she moved a year ago. Born in Mobile, Ala., she came here a year ago from St. Petersburg. She was a Spanish and English teacher; and a member of Kappa Delta Pi and Sigma Delta Pi. Survivors include her husband Manuel; a daughter, Alexandra J. Sevillano of Clearwater; and a sister, Darian K. Walker of Clearwater.