Clavicle is genetics, wide clavicles is a good genetic trait for a bodybuilder but Phil Heath, arguably one of the most dominant Mr olympias had very narrow clavicles. When your clavicles are narrow, the fix is to work on building rounder wider shoulders without tons of upper trap development. When the traps become overpowering on a physique with narrow clavicles it makes you look more narrow. So you want to focus on building up your upper back, chest and shoulders, but not so much your traps.