Yes, SPLASHER is a Scrabble word!

Letter values in Scrabble US: S 1, P 3, L 1, A 1, S 1, H 4, E 1, R 1.

Is it a valid word?

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

a protective covering over or beside a wheel to protect the upper part of a vehicle from splashes of mud
protective covering consisting of a panel to protect people from the splashing water or mud etc.