cling on for dear life

Translations
цепляться изо всех сил
She clung on for dear life as the roller coaster sped down the track.
Она цеплялась изо всех сил, когда американские горки мчались по рельсам.
Definitions
To hold onto something very tightly, usually out of fear or desperation, in order to avoid danger or harm; often used figuratively to describe someone trying very hard to keep or maintain something important to them.