Yes, SHORTSTOP is a Scrabble word!

Letter values in Scrabble US: S 1, H 4, O 1, R 1, T 1, S 1, T 1, O 1, P 3.

Is it a valid word?

SHORTSTOP is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

(baseball) the person who plays the shortstop position
the fielding position of the player on a baseball team who is stationed between second and third base