Student or Learner
"Lewis Hamilton is all over the news after a nail-biting Grand Prix in Brazil saw him become the youngest ever Formula One World Champion. "
Is "after" conjunction?
Is "a nail-biting Grand Prix in Brazil" subject?
Is " saw" a verb?
(Not a teacher)
This sentence basically says, "Lewis Hamilton is famous as the youngest-ever Formula One world champion after he won a suspenseful Grand Prix in Brazil." Here, "saw" is used idiomatically to mean "caused" or "resulted in". Other examples of this construction include: "The crash of the stock market saw millions of people lose their investments" and, "The end of the nineteenth century largely saw the disappearance of the cowboy way of life." It can also be used in the present/future: "Global warming will see the extinction of many polar animals." Obviously, a Grand Prix, a stock market crash, or the end of the century cannot "see" in the normal sense but the aftermath of each of these is visible.
I believe "after" is used as a conjuction here. "Grand Prix [win]" is used as a subject although it was the win (not stated but implied) that was the actual subject. Finally, "saw," as the past tense of the verb "to see"is the verbal part of this phrase.
Sorry you asked?