Che Playa Hostel seems to fit the bill for a safe, clean, and affordable stay in Playa del Carmen. It offers small rooms for solo female travelers, with a maximum capacity of 4-6 people, and a female-only dorm option.
The hostel is also close to the beach and has a rooftop bar with a pleasant evening atmosphere. This makes it an ideal choice for a solo female traveler looking for a budget-friendly and social stay.