Yes, CRENATURE is a Scrabble word!

Letter values in Scrabble US: C 3, R 1, E 1, N 1, A 1, T 1, U 1, R 1, E 1.

Is it a valid word?

CRENATURE is a valid word in the official Scrabble dictionary (US) and the UK Scrabble Dictionary, but not in Words with Friends (ENABLE).

one of a series of rounded projections (or the notches between them) formed by curves along an edge (as the edge of a leaf or piece of cloth or the margin of a shell or a shriveled red blood cell observed in a hypertonic solution etc.)