An embedded clause is a sentence within a sentence:
The work you did was excellent. The green hills that surround the town are covered with flowers.
All clauses contains a subject and a verb:
The work was excellent.
(Main Clause: subject 'work', verb 'was')
(Embedded Clause: Subject 'you', verb 'did')
The green hills are covered with flowers.
(Main Clause: Subject 'hills', verb 'are covered')
that surrround the town
(Enbedded Clause: subject 'that', verb 'surround')
An embedded clause cannot stand on its own. It needs to be part of another sentence. In the examples below the embedded clause is underlined, the subject and its verb are in blue, and the main clause is in pink:
After Jan earned eight days of vacation time, she took her handicapped nephew to Cinnamon Bay because he loved to swim.
When evening came, she would cook whatever he wanted on the little camp stove that came with their rented tent.