The word underselling 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: 20
Highest Scoring Words With Friends™ Plays In The Letters underselling
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Seven Letter Word Alert: (75 words)
deleing, deluges, dengues, deniers, dinners, duelers, dueling, dueller, dulling, eluders, eluding, endings, endures, engined, engines, ensuing, ensured, gelders, genders, genuine, gilders, girdles, girnels, gliders, greisen, grilled, grilles, grinned, guilder, guldens, gullied, gullies, gunners, indulge, insured, ledgers, leering, legends, leisure, lenders, lending, lensing, lindens, lingers, linseed, needing, nursing, redline, reeling, regilds, reglued, reglues, reguide, reigned, relined, relines, rending, residue, reusing, rulings, runnels, sedgier, seeding, selling, sending, singled, slender, slinger, sullied, sunnier, undines, unlined, unreels, unrisen, unsling