double
The letters spell the word double.
Double.
The structure is that the letters for a word are mixed up. You then need to use all of the letters and rearrange the letters to spell a word.
I think you might mean an anagram, where letters from a word are mixed up to form a new one
diary
CRUZEIRO
ferry.
Mouse.
keckle
Unscrambled, the letters 'scinek' spell 'sicken'.
The letters errtuesa spell the words 'treasure' and 'austerer'.
REST, ERST, TRES, RETS