Yes, ORCHESTRATION is a Scrabble word!

Letter values in Scrabble US: O 1, R 1, C 3, H 4, E 1, S 1, T 1, R 1, A 1, T 1, I 1, O 1, N 1.

Is it a valid word?

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

an arrangement of a piece of music for performance by an orchestra or band
the act of arranging a piece of music for an orchestra and assigning parts to the different musical instruments
an arrangement of events that attempts to achieve a maximum effect