The term ENVELOPE PART is composed of two crossword solutions, CLASP (5 letters) and FLAP (4 letters). A CLASP is a fastening device used to secure the contents of an envelope, usually made of metal or plastic. A FLAP is a piece of paper or material that is folded over the opening of an envelope to close it. The FLAP is usually secured with a CLASP. Together, the CLASP and FLAP form an important part of the envelope, ensuring that the contents remain secure.