The common sense of this word (the second one) is actually the figurative one. It makes perfect sense if one thinks about it, but I hadn’t ever bothered to think about this word very hard.
1. Second or later mowing; the crop of grass which springs up after the mowing in early summer. Also attrib. (See also AFTERGRASS, AFTERCROP.)
2. fig. Esp. a state or condition left by a (usu. unpleasant) event, or some further occurrence arising from it.