Hinge on
Definition 1 of 1
Pro Tip 1/3Context Matters
Hint: 'hinge on' is used when one situation directly affects another. 
Their reunion hinges on his return from abroad.
Pro Tip 2/3Critical Condition
It expresses that one crucial factor will determine the outcome of something. 
Our vacation hinges on the weather forecast.
Pro Tip 3/3Not Literal
'Hinge on' isn't about actual hinges; it's figurative for a pivotal or decisive point. 
Admission to the club hinges on membership approval.