Yes, REVERSAL is a Scrabble word!

Letter values in Scrabble US: R 1, E 1, V 4, E 1, R 1, S 1, A 1, L 1.

Is it a valid word?

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

a change from one state to the opposite state
an unfortunate happening that hinders or impedes; something that is thwarting or frustrating
turning in an opposite direction or position
a decision to reverse an earlier decision
a judgment by a higher court that the judgment of a lower court was incorrect and should be set aside
turning in the opposite direction
the act of reversing the order or place of
a major change in attitude or principle or point of view

Also: black eye, turn around, change of mind, flip-flop, about-face, volte-face, policy change.