Yes, COMBINATION is a Scrabble word!

Letter values in Scrabble US: C 3, O 1, M 3, B 3, I 1, N 1, A 1, T 1, I 1, O 1, N 1.

Is it a valid word?

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

a collection of things that have been combined; an assemblage of separate parts or qualities
a coordinated sequence of chess moves
a sequence of numbers or letters that opens a combination lock
a group of people (often temporary) having a common purpose
an alliance of people or corporations or countries for a special purpose (formerly to achieve some antisocial end but now for general political or economic purposes)
the act of arranging elements into specified groups without regard to order
the act of combining things to form a new whole