well kept 
adjective
1(Especially of property) kept clean, tidy, and in good condition: the grounds were beautiful and well kept...
- Their balcony, though small, used to be neat and tidy with well-kept hanging baskets.
- Lunch at a table under a tree in an immaculately clean, open and well-kept area near the car park was welcome for hungry tummies after the exercise.
- The carriage had cost £500, bought 30 years ago from a wheeler-dealing butcher in Yeadon, money well spent too, judging by its well-kept condition.
2(Of a secret) not told to anyone or made widely known: the exact date was a well-kept secret...
- Hidden deep in the North York Moors is a well-kept secret - The Orange Tree, the perfect remedy for the stresses and strains of modern life.
- At present, he feels that ‘Ukraine is an emerging attraction to filmmakers’, whereas Bulgaria has remained a relatively well-kept secret.
- One of backcountry skiing's well-kept secrets is that skiers get caught in avalanches with fair regularity, though they are often small and rarely fatal.