The word underlings 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 underlings
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Seven Letter Word Alert: (33 words)
dinners, dueling, eluding, endings, ensuing, gilders, girdles, girnels, gliders, grinned, guilder, guldens, gunners, indulge, insured, lending, lensing, lindens, lingers, nursing, regilds, rending, reusing, rulings, runnels, sending, singled, slinger, sunnier, undines, unlined, unrisen, unsling