It's a wordplay that doesn't really answer the clue.

Every word is key except for the: "Watches Grissom crossing the road" (6).

Grissom is Virgil Grissom, known as Gus. So GUS must be in there.

There is a type of road crossing known as a T crossing. So T must be in there.

Watches brings to mind audiovisual equipment, AV for short. So AV is there too.

Which spells GUSTAV, the name for which Gus is traditionally short.

At least that's how I make sense of CE's answer. CE probably has a better explanation.