Yes babies can eat clam chowder as long as the baby is eating solid foods and is at least 9 months of age.
Some babies may not be ready to eat clam chowder until they are 10 to 11 months of age but as long as the baby is 9 months of age and they are eating some other solid foods then they can eat clam chowder safely.
My babies ate some clam chowder when they were 9 months old and they loved it.
Babies can eat almost anything that adults can as long as they have some teeth and can eat solid foods.
If the baby is not ready to eat solid food then they cannot eat clam chowder.
Each baby is different and some babies will like the clam chowder and some babies will not like the clam chowder.
Just try them with a little bit of the clam chowder and be prepared for a mess.