What Stan Lee has in many a Marvel movie

CAMEO

Look for the brief, often playful appearance by a famous creator that fans eagerly spot in superhero films.

This clue refers to Stan Lee’s famous brief appearances in Marvel movies, known as "cameos." A cameo is when a well-known person shows up in a small, often uncredited role—something Lee did in nearly every Marvel film as a fun nod to fans. The wordplay is straightforward, using "many a Marvel movie" to hint at his recurring habit. If you’ve seen films like Spider-Man or Avengers, you’ve likely spotted his playful little moments.