Matthew J. Kirby, who describes himself in the backmatter bio as a school psychologist, who was encouraged by his wife to get back into writing. Clockwork is his first endeavor. So that worked out pretty good for Kirby; since this book was published in 2010, Kirby has written a handful of additional young adult books, and now lists himself as a former school psychologist.
Clockwork follows the trials of three young people in what seems like the mid- to late-1800s, in an unnamed American city, that could be New York. Kirby notes in the backmatter that this story was inspired by a boy who was kidnapped from Italy and sold into slavery as a busker in New York, who eventually escaped from his padrone, and testified against him, which led to the outlawing of padroni and the freedom of the kids enslaved by them.
So this kid is the inspiration for one of the trio. The second is a girl who had to leave school and go to work to support her family after her father suffered a stroke and could no longer work. The third is an apprentice clock maker, rescued from an 'orphanage' which was really a sweatshop using child labor to manufacture fabric. So you can see that these three teens have come from similar, difficult backgrounds, they meet one another individually, within a few days, and soon strike up friendships, and then discover they all know one another. They quickly band together to help each other overcome their diversity, in ways that are frankly impossible for any kid to dream of.
I think is basically what sets this book apart as the work of a novice: Cinderella stories are fun to read, and its fun to suspend disbelieve for the duration. But asking us to believe that three separate kids can meet, put their heads together for a few days, outsmart all of the mean and evil adults in their lives, disobey, lie to, fail to trust, and even steal from, their fairy godmothers (the good people that suddenly appear in their lives) and then be not only forgiven, but each is transformed into the metaphorical princess for their trouble, is asking a little too much. But I guess this story is for middle schoolers.
The writing is a little telly rather than showy, which makes it read a little flat, but if you have a tween that likes this kind of thing, they may enjoy it.