Dragnets.
How can the word be 3 letters long if "sand" alone is 4? .
Flank
Daffodill
Oust.
diligent
varcious
skinnier
Mock.
oblong.
isogloss
One word that fits your criteria is "distant." It starts with the letter 'd,' ends with 't,' and contains seven letters.
Of course, there are many 8 letter words that begin with the letter Y. One is yardwork. A word that is 10 letters long and starts with an N could be nauseating