Yes, SHAKIER is a Scrabble word!

Letter values in Scrabble US: S 1, H 4, A 1, K 5, I 1, E 1, R 1.

Is it a valid word?

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

inclined to shake as from weakness or defect
vibrating slightly and irregularly; as e.g. with fear or cold or like the leaves of an aspen in a breeze
not secure; beset with difficulties