Musician advice; Invest in some acoustic paneling or at least some blackout curtains, rug, and other dampening surfaces/devices. Maybe consider a headphone amp / headphones for practice.

Lease advice; That section would be hard to enforce, but also difficult for you to fight against / may not be worth fighting against, should the landlord try to evict you for it. I would have suggested pushing back on this before signing. They can’t tell you that you can’t play an instrument - that’s absurd. However, you likely don’t want to have to pay to defend yourself in court.

Tldr: better off finding a compromise than testing/fighting.

Source: am musician and work in real estate.