Restrictive clauses are relative to adjective clauses.
1. 'with the golden hair' would be describing the Girl, because her hair is Golden.
2. What describes the dog ? The dog 'that ate my homework'
3. What describes the muffins ? The muffins 'that have cherries'
4. What describes the smile ? The smile that she gave them was 'beautiful'
The adjectives phrases are in my apostrophes, hope you understand what restrictive clauses are now. :)