Yes, WINDER is a Scrabble word!

Letter values in Scrabble US: W 4, I 1, N 1, D 2, E 1, R 1.

Is it a valid word?

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

a worker who winds (e.g., a winch or clock or other mechanism)
mechanical device used to wind another device that is driven by a spring (as a clock)
mechanical device around which something can be wound