Yes, CLOCKWORK is a Scrabble word!

Letter values in Scrabble US: C 3, L 1, O 1, C 3, K 5, W 4, O 1, R 1, K 5.

Is it a valid word?

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

any mechanism of geared wheels that is driven by a coiled spring; resembles the works of a mechanical clock