The word cleanliest 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: 16
Highest Scoring Words With Friends™ Plays In The Letters
Seven Letter Word Alert: (27 words)
cantles, castile, cellist, cleanse, clients, elastic, elastin, entails, entices, install, laciest, lancets, lateens, leanest, lenites, lentils, license, lineate, lintels, nailset, salient, scalene, silence, stencil, tallies, tellies, tensile