1. to make or become more neat, stylish, or well-dressed in appearance
Usage: often used with ‘up’
2. to make or become more intelligent or alert
Usage: often used with ‘up’

Examples

• She decided to smarten up her appearance before the job interview.
• The new paint job really smartened up the old house.
• He needs to smarten up his act if he wants to keep his job.
• The training program helped smarten up the new employees.
• A fresh haircut will smarten you up nicely.
• The company is trying to smarten up its image with younger customers.