1921 poem by Elinor Wylie, 10 letters
Close off, as a tomb, 6 letters
Close tight, 6 letters
Make airtight, 6 letters
Make airtight, perhaps, 6 letters
Make hermetic, 6 letters
Make watertight, 6 letters
Make watertight, maybe, 6 letters
Shrink-wrap, 6 letters
Shrink-wrap, e.g., 6 letters
Thoroughly confine, 6 letters