Thank you for your help!
I tried to push the wire further into the 'boot' but it was glued it so i tried to twist it to break the seal and then i was able to pull it out slightly.
At which point I could see a metal ring (I think) at the base of the boot, so it looks like the clip you mention is missing (I attach a new photo).
I think now I have this information I can go to a hardware store - or actually I know a place that handles Honda repairs so I can call them up and ask them if they have a suitable replacement part.
Thanks again for your fast responses!