CLEF

Yes. "CLEF" is in the ENABLE word list, accepted by Words With Friends and most open Scrabble apps. It scores 9 points in Scrabble and 11 points in Words With Friends.

In Scrabble, "CLEF" is worth 9 points before bonuses. In Words With Friends, it's worth 11 points. Played on a triple-word-score, the Scrabble value becomes 27.

A symbol found on a musical staff that indicates the pitches represented by the lines and the spaces on the staff

No, "CLEF" has no anagrams in the ENABLE dictionary — it's the only word that can be formed from its exact letters.