a/the bright spot
A positive occurrence in an otherwise sad or negative situation. His granddaughter coming to visit him in the nursing home was always a bright spot in Jim's day.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
a/the ˈbright spota good or pleasant part of something that is unpleasant or bad in all other ways: The win last week was the only bright spot in their last ten games.
Farlex Partner Idioms Dictionary © Farlex 2017