الطَّالِبُ الْمُجْتَهِدُ حَاضِرٌ — The diligent student is present.
الطَّالِبُ: definite, nominative mubtadaʾ.
الْمُجْتَهِدُ: nominative naʿt agreeing in definiteness.
حَاضِرٌ: nominative khabar; it completes the assertion.
Parse the whole sentence and intended meaning; do not automatically call the second word a predicate.