The phrase "young thief" refers to a person who is both young in age and steals or takes things that do not belong to them without permission. Full definition
The film is about a pair of clever young thieves who rob the houses of rich people, but one day one of them winds up at a home where a woman is being held against her will. (firstshowing.net)
[1] Bowlby himself was interested in the role played in delinquency by poor early relationships, and explored this in a study of young thieves. (newworldencyclopedia.org)
On the streets of Marseille, 1961, several young thieves take 12 - year - old Charlie under their wing and start teaching him the ropes. (booklistonline.com)