Yes, you can.
However, making a change to a library clause applies that change to all uses of the clause. Not only all future uses, but also all uses of the clause in existing documents as well. That is why it can be dangerous to change a library clause. There is, however, a way to work around this to make your entire clause conditional for your specific document.
- Insert the clause into your document.
- Select it and click the pencil icon, then click “convert to independent ad hoc clause”.
- Add the condition you want to the “enabled?” property of the ad hoc clause.
- Hit save.
After going through these steps, your clause should have become conditional (using the condition in the ad hoc clause).
You can do this for a clause, subclause or even clauses used in an enumeration/bullet list.