Yes, TAMARILLO is a Scrabble word!

Letter values in Scrabble US: T 1, A 1, M 3, A 1, R 1, I 1, L 1, L 1, O 1.

Is it a valid word?

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

South American arborescent shrub having pale pink blossoms followed by egg-shaped reddish-brown edible fruit somewhat resembling a tomato in flavor

Also: tree tomato.