يَا طَالِبَ الْعِلْمِ!
Translation: O seeker of knowledge!
يَا: vocative particle.
طَالِبَ: accusative construct vocative, first term of iḍāfa.
الْعِلْمِ: genitive second term.
This is an added teaching example. Recognize the genitive construction, not merely its visible fatḥa.