Yes, BONDAGE is a Scrabble word!

Letter values in Scrabble US: B 3, O 1, N 1, D 2, A 1, G 2, E 1.

Is it a valid word?

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

the state of being under the control of a force or influence or abstract power
the state of being under the control of another person
sexual practice that involves physically restraining (by cords or handcuffs) one of the partners