Speedo help

There will be very little length left to hook it up with the cluster out.
In fact you probably won't even be able to see it to try to hook it up with the cluster out at all.
If you really want to pull the cable out, do it from in the engine compartment and ease it out being carefull not to rip out wires and stuff. Just ease it out.
And consider having to snake it back in there afterwards.

There is a little clip as you suspect on the plastic end that snaps off, then they won't clip on anymore.
Mine is like that, but I just made sure the cable was free enough to stay in place and not try to pull off the speedo head. (been that way for over a year now and works just fine)

Of course there is always the option of a new one.