For dear life
Definition 1 of 1
Pro Tip 1/3High Stakes
Use 'for dear life' when the situation feels critical or as if a serious loss is at risk. 
He fought off the attacker for dear life.
Pro Tip 2/3Extreme Urgency
This phrase suggests immediate action is needed, the same as an emergency. 
She grabbed the last parachute and jumped out for dear life.
Pro Tip 3/3Not Literal
'For dear life' can be figurative, not just physical danger, but for preserving something valuable. 
He argued for dear life to save his career.