Yes, DEFECTION is a Scrabble word!

Letter values in Scrabble US: D 2, E 1, F 4, E 1, C 3, T 1, I 1, O 1, N 1.

Is it a valid word?

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

withdrawing support or help despite allegiance or responsibility
the state of having rejected your religious beliefs or your political party or a cause (often in favor of opposing beliefs or causes)