Yes, spelt is a Scrabble word!

Verb

1. Orally recite the letters of or give the spelling of

2. Indicate or signify

3. Write or name the letters that comprise the conventionally accepted form of (a word or part of a word)

4. Relieve (someone) from work by taking a turn

5. Place under a spell

6. Take turns working

Noun

1. Hardy wheat grown mostly in Europe for livestock feed