There are 12 words that start with 'clow'.
| clown | clowns | 
| clowder | clowned | 
| clowders | clownery | 
| clowning | clownish | 
| clowneries | clownishly | 
| clownishness | clownishnesses | 
Note: These 12 words that start with 'clow' are found from the USA & Canada version of the tournament Scrabble word list.