Yes, MINDERS is a Scrabble word!

Letter values in Scrabble US: M 3, I 1, N 1, D 2, E 1, R 1, S 1.

Is it a valid word?

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

someone (usually in totalitarian countries) who is assigned to watch over foreign visitors
a person who looks after babies (usually in the person's own home) while the babys' parents are working

Also: baby minder.

Not playable in Scrabble US: BABYMINDER.