It's often found in English words related to the idea of enclosing, containing, or shutting off.
Here are some examples:
* Exclude: To shut out or keep out.
* Include: To take in or contain.
* Conclude: To bring to an end.
* Seclude: To keep apart or isolate.
* Recluse: A person who lives in seclusion.
So, the basic meaning of "clude" is to close off or to bring to an end.