As part of a clutch replacement, a skilled mechanic will first examine your clutch and gearbox, to make sure that these parts are the cause of the issues you have been experiencing.
After determining that the clutch is the culprit, the mechanic will next unhook the battery and disconnect the clutch and/or hydraulic slave cylinder, so that they can stabilise the engine. Once they have unbolted the pressure plate, they can look for any leaks or damages, and clean or replace these parts accordingly.
Lastly, the mechanic will rebuild the front of your vehicle, and test your clutch to ensure it is functioning correctly.