きれい
I have talked about quite a few English words which requires a few different Japanese words to translate them but today I will do the opposite. The Japanese word きれい has a few meanings in English.
pretty or beautiful
きれいな人(ひと) = a beautiful person
きれいな景色(けしき) = a pretty view
clean or pure
きれいな水(みず) = clean water
きれいな空気(くうき) = pure air
tidy or neat
きれいな部屋(へや) = a tidy room
きれいな字(じ) = neat handwriting
By the way, even though きれい ends in い, it is a な-adjective, so the negative of きれい is not きれくない but きれいじゃない.
Having said that, きれくない is truly and surely starting to get used. Maybe in 10 years time, きれくない may be accepted as being correct.