Crossword clues for lighten up
Wiktionary
lighten up
vb. (context idiomatic English) To become less serious and more cheerful or casual; to relax.
WordNet
Usage examples of "lighten up".
Steve had constantly told her to lighten up, and his tone had sometimes been full of impatience.
That sense of doom had hung about the boy so palpably that there had been times when Richard had wanted to hug him, to tell him to lighten up a little bit, that sometimes there were happy endings and the good didn't always die young.