Yes, ESTABLISH is a Scrabble word!

Letter values in Scrabble US: E 1, S 1, T 1, A 1, B 3, L 1, I 1, S 1, H 4.

Is it a valid word?

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

set up or found
set up or lay the groundwork for
establish the validity of something, as by an example, explanation or experiment
institute, enact, or establish
bring about
place
build or establish something abstract
use as a basis for; found on

Also: set up, lay down.