Yes, DISCLOSE is a Scrabble word!

Letter values in Scrabble US: D 2, I 1, S 1, C 3, L 1, O 1, S 1, E 1.

Is it a valid word?

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

make known to the public information that was previously known only to a few people or that was meant to be kept a secret
disclose to view as by removing a cover

Also: let on, bring out, give away, let out.