"There is only one church in the city."
Translation:Det finns bara en kyrka i staden.
You must mean ende, which is the masculine form of enda. (The masculine form of adjectives is totally optional, in some regions it is never used). It is used as a definite adjective in constructions like det var enda gången 'it was the only time' or du är den enda för mig 'you are the only one for me'. It shows up in the hint here because there is a hint somewhere else saying that "the only one" can mean den enda/ende, like in my second example, but it's not the same kind of 'only one' here.