What One Does to Their Seatbelt When in a Plane

This page is the CodyCross answer for the clue below from Germany, Group 2181, Puzzle 2 (Currywurst).

Question is: What One Does to Their Seatbelt When in a Plane

and the answer is: FASTEN

Word Meaning:

FASTEN — (ambitransitive) To attach or connect in a secure manner.

Definitions from Wiktionary.