Wiktionary
fair enough
interj. (context idiomatic English) (non-gloss definition: An expression used to concede a point; denotes that, upon consideration, something is correct or reasonable; an expression of acknowledgment or understanding.)
Usage examples of "fair enough".
But it was a fair enough piece of work, and in many respects satisfying.
And Gualtieri, who had long noted with approval the mien of a poor girl that dwelt on a farm hard by his house, and found her fair enough, deemed that with her he might pass a tolerably happy life.
It wasn't a pleasant laugh, but that was fair enough, because she wasn't a pleasant person.