keep (your)/both feet on the ground

to not have your character spoilt by becoming famous or successful.

Friends say she's kept her feet firmly on the ground - fame hasn't changed her.

• battle of wits
• be a athlete in the making
• be a [athlete/star/writer etc.] in the making
• be a barrel of laughs
• be a bed of nails
• be a bit much
• be a blessing in disguise
• be above board
• be a bundle of laughs
• be a bundle of nerves
• be a chapter of accidents
• be a closed book
• be a [crisis/disaster etc.] in the making
• be a crisis in the making
• be a crock of shit
• be a cut above
• be a cut above someone
• be a cut above something
• be a dab hand
• be a dead cert
• be a dead loss
• be a dead ringer for
• be a dead ringer for someone
• be a dead ringer for something
• be a different kettle of fish