In a medium-size saucepan, melt butter. Blend in flour and add milk and chicken broth. Cook and stir until mixture thickens and bubbles, and continue cooking for 1 minute more.
Add lemon juice, snipped parsley, and onion. Stir in celery salt and a dash each of pepper, paprika, and nutmeg. Cool.
In a large mixing bowl, combine sauce with the ground turkey. Chill thoroughly. With wet hands, shape mixture into balls. Roll balls one at a time in bread crumbs.
Lightly shape balls into cones. For each croquette, dip it into the mixture of egg and water, then roll in bread crumbs. Again, dip croquette in egg/flour and roll in bread crumbs. Fry croquettes in deep-fat fryer for approximately 3 minutes or until brown. Drain. Serve with turkey gravy.