Yes, DEVOLUTION is a Scrabble word!

Letter values in Scrabble US: D 2, E 1, V 4, O 1, L 1, U 1, T 1, I 1, O 1, N 1.

Is it a valid word?

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

the process of declining from a higher to a lower level of effective power or vitality or essential quality
the delegation of authority (especially from a central to a regional government)

Not playable in Scrabble US: DEVOLVEMENT.