Iberian ruler and knight guarding carved holy figure (10)

I haven't cracked this one yet — but the brilliant team at Times for the Times have:

HOLY* (the anagram indicator is ‘carved’) in PEDRO N; Pedro of Castile, known as Peter the Cruel or Peter the Just – presumably, depending on how you played your cards – was the King of Castile and León from 1350 until his death in 1369