unseal
The answer is an envelope. It contains a letter.
Gwab is an Arabic word that means answer, reply, envelope or a postal letter
The word its is a possessive form of the pronoun 'it', used as an attributive adjective.It is less awkward than saying 'Put the letter in the letter's envelope' or '... the envelope of the letter'.
An 8 letter word, with just one letter in it, is ENVELOPE. 8 letters in the word, 1 letter inside the envelope.
Envelope is the answer.
envelope
If the question means 'one other letter', I believe the answer is eye. (Adds one letter Y.) If the question is a riddle, the answer is 'envelope' as it begins and ends with 'e', and it contains a letter.
Envelope.
envelope
PATENT
The word is "envelope" (which usually holds only one letter).
Envelope