DALLAS — Defense lawyers for James Lebus are to cross examine a star prosecution witness in Lebus’ burglary trial in Dallas today. The witness, Clyde Bums, has testified he broke into metallic development corporation of Wichita Falls and stole various precious metals at the urging ofLebus. Other testimony yesterday showed more than 25 thousand dollars worth of old, silver and palladium were stolen from the safe of the Wichita Falls company in December 1974.