Yes, tut is a Scrabble word!
...and is worth 3 points in Scrabble, and 4 points in Words with Friends
tut
Verb
1. Utter `tsk,' `tut,' or `tut-tut,' as in disapproval
What Scrabble words can I make with the letters in tut?
2 Letter Words
Verb
1. Utter `tsk,' `tut,' or `tut-tut,' as in disapproval
2 Letter Words