* σαφής (safēs): This is a good general word for "clear," meaning unambiguous, distinct, or easily understood. It works well for things like "a clear explanation" (σαφής εξήγηση - safēs exēgēsi).
* καθαρός (katharós): This means "clean," "pure," or "clear" in the sense of being free from impurities. It's appropriate for things like "clear water" (καθαρό νερό - katharó nero).
* διαυγής (diaugēs): This translates to "transparent," "pellucid," or "clear" as in something allowing light to pass through. It's suitable for describing things like "clear glass" (διαυγές γυαλί - diaugēs gialí).
* φανερός (phanerós): This means "evident," "obvious," or "clear" in the sense of being readily apparent. It works for things like "a clear indication" (φανερή ένδειξη - phaneri endeixi).
To choose the right word, you need to consider what kind of "clear" you are trying to express.