Yes, METAPHOR is a Scrabble word!

Letter values in Scrabble US: M 3, E 1, T 1, A 1, P 3, H 4, O 1, R 1.

Is it a valid word?

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

a figure of speech in which an expression is used to refer to something that it does not literally denote in order to suggest a similarity