Synonyms for Well-kept:

adj.

clean (adjective)
orderly, neat, tidy, trim.
neat (adjective)
shipshape.
shipshape (adjective)
uncluttered, ordered.

n.

tidy (noun)
neat, just so, orderly, uncluttered, ordered, Manicured, organized.
well-kept (noun)
maintained, kept up, preserved, shipshape, trim, tidy.

Other synonyms:

tidy
ordered, neat, organized, uncluttered, orderly, Manicured, tidy.
Other relevant words:
orderly, neat, uncluttered, Manicured.