Clamp is a pretty small brand from Tokyo. They produce a lot of workwear-friendly items (chore coats, overalls, lots of denim) in a variety of unusual silhouettes. For example, a henley might still have three buttons, but they've been shifted to the side instead of being positioned vertically on the chest.
I actually don't know too much about them. Their sparse website isn't easy to find (it's
https://clamp.link/) and the designer's name doesn't come up in brand descriptions; not to mention, they only mention two stockists on their website, one of whom doesn't seem to stock them anymore. According to what I figure out from their mission statement, they take flintstone from connections, things that work together. Their clothes, I think, are intended to tie together a look or a wardrobe by offering a wearable, yet differentiated, take on staple pieces - they're intended to 'connect' with other clothes easily.
They settle in nicely with other workwear-skewing labels like Class, Salvy;, RDV O GLOBE, and Bukht.