1.
In a vehicle such as a car or a bus, the ~ is the seat where the person who is driving the vehicle sits.
He got into the ~ and started the engine.
= driver’s seat
N-SING: usu the N
2.
If you say that someone is in the ~, you mean that they are in control in a situation.
At 69 he is as firmly in the ~ of the company as ever.
PHRASE: usu v-link PHR, PHR after v