The word claystones is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 17
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (31 words)
acetyls, acolyte, alecost, ascents, cantles, castles, closest, closets, cotylae, cotyles, coyness, cyanose, ecstasy, encysts, lactone, lactose, lancets, latency, leantos, locates, lysates, octanes, octynes, scantly, secants, solaces, stances, stanols, systole, toyless, tyloses