I manage to get the clip out but it still happen when i put it back.Looks to be intact.
The black 'clip' that's currently on the back of the key, should connect to the keyboard itself - latching over the hooks/clips, and the keycap should press down onto it.
I'm not sure if you can remove the clip from the back for the key without risking damage though.
No, you do not need glue.