a bright spark
A person who is regarded as clever or intelligent. The term can also be used sarcastically to mean the opposite. Primarily heard in UK, Australia, New Zealand. Timmy's the bright spark of the family—he graduated at the top of his class. Some bright spark at the auto repair shop forgot to tighten the lug nuts on my wheels after he rotated my tires.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
a bright sparkmainly BRITISH
A bright spark is a clever person. But the girl from Dublin is not just a pretty face. The bright spark is studying archaeology and the history of art at UCD. Some bright spark at the club seems to think that the best way to attract young fans is to turn the football stadium into a theme park for the day. Note: This expression is usually used to mean the opposite, referring humorously to a person with stupid ideas.
Collins COBUILD Idioms Dictionary, 3rd ed. © HarperCollins Publishers 2012