Yes, SKINHEADS is a Scrabble word!

Letter values in Scrabble US: S 1, K 5, I 1, N 1, H 4, E 1, A 1, D 2, S 1.

Is it a valid word?

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

a youth subculture that appeared first in England in the late 1960s as a working-class reaction to the hippies; hair was cropped close to the scalp; wore work-shirts and short jeans (supported by suspenders) and heavy red boots; involved in attacks against Asians and football hooliganism
a young person who belongs to a British or American group that shave their heads and gather at rock concerts or engage in white supremacist demonstrations

Not playable in Scrabble US: BOOTBOYS.