This is on the intake pipe leading to the throttle body on Alfa Romeo Giulietta. This is on the side closer to turbo, rather than throttle body. The sensor next to it is the boost sensor. It does not seem to be a worm clamp. Hope someone is familiar with it.
I think that's called an Oeticker clamp, and it's an inexpensive "one-time-use-only" band of steel that is slightly larger than the OD of the hose, with a little squared-off loop on one section.
It is "clamped" at the factory with a pair of pliers (or perhaps an automated machine) that looks something like barb wire cutting pliers. It's inexpensive and has only one part.
Solar Mike's comment is spot on; break it carefully as not to damage the hose, and replace with a quality worm-drive or similar. It was probably never or rarely expected to be taken apart.
OEM's are now exploring various one-piece clamps, some of which are reusable, like the EzyClik style on newer Mercedes Benz. It's cost effective for them, but it's a curse to a mechanic that now has to buy special tools to deal with the new "better mousetrap" styles of automotive hose clamping.