There are 11 words that start with 'claus'.
| clause | clausal | 
| clauses | claustra | 
| claustral | claustrum | 
| claustrophobe | claustrophobes | 
| claustrophobia | claustrophobic | 
| claustrophobias | |
Note: These 11 words that start with 'claus' are found from the USA & Canada version of the tournament Scrabble word list.