Falls behind

The answer to the crossword clue ‘Falls behind is LAGS‘ is quite simple. The word ‘lags‘ can mean to fall behind or to fail to keep up with the pace of the others. Therefore, when someone is lagging, it implies that they are trailing behind the rest of the group, either in terms of speed, progress or accomplishment. In the context of the crossword question, ‘Falls behind is LAGS‘, the two phrases are being equated to each other, or in other words, the answer is suggesting that the phrase ‘falls behind‘ can be replaced by the word ‘lags‘.