Yes, CROSSHEAD is a Scrabble word!

Letter values in Scrabble US: C 3, R 1, O 1, S 1, S 1, H 4, E 1, A 1, D 2.

Is it a valid word?

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

a heading of a subsection printed within the body of the text
metal block that connects to a piston; it slides on parallel guides and moves a connecting rod back and forth

Not playable in Scrabble US: CROSSHEADING.