Where should the hyphen be placed?

Eager for the game to start again, he watched the half time clock.

Eager for the game to start again, he-watched the half time clock.

Eager for the-game to start again, he watched the half time clock.

Eager for the game to start-again, he watched the half time clock.

Eager for the game to start again, he watched the half-time clock.

Eager for the game to start again, he watched the halftime clock.

The correct placement of the hyphen is:

Eager for the game to start again, he watched the half-time clock.