Hang on by (one's) fingernails verb phrase
To hold tightly to something with one's fingernails to avoid falling
As soon as he slipped and narrowly fell, he hung on by his fingernails.
To be difficult to avoid problems or failure
I am working as a customer service representative who deals with a ton of complaints and questions from customers, give customers information about products and services, take orders, and process returns. Sometimes I really feel like I'm hanging on by my fingernails.
To avoid, or attempt to avoid, a specific problem by pretending not to see it.
The verb "hang" should be conjugated according to its tense.