dedicated

An dedicated person or thing has complete and unwavering commitment to something. A dedicated employee often works long hours with no complaints.

When we say someone is dedicated, we usually mean they have a strong focus on their job, hobby, or cause. For example, a dedicated teacher will put in extra effort outside of class time to help students succeed. On the other hand, a car can be described as a dedicated off-roader if it's been modified for rugged terrain use and isn't suited for normal driving conditions.