Yes, TREASURY is a Scrabble word!

Letter values in Scrabble US: T 1, R 1, E 1, A 1, S 1, U 1, R 1, Y 4.

Is it a valid word?

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

the funds of a government or institution or individual
the government department responsible for collecting and managing and spending public revenues
negotiable debt obligations of the United States government which guarantees that interest and principal payments will be paid on time
the British cabinet minister responsible for economic strategy
the federal department that collects revenue and administers federal finances; the Treasury Department was created in 1789
a depository (a room or building) where wealth and precious objects can be kept safely

Also: treasury obligations, first lord of the treasury, department of the treasury, treasury department, united states treasury.