Replacing a clutch cable is generally not considered a massive job for a professional mechanic, but its difficulty can vary significantly depending on the vehicle's make and model.
On a scale of automotive repairs, it's often considered a moderate job. The challenge lies in accessibility. The mechanic needs to route the new cable from the clutch pedal inside the cabin, through the firewall, and all the way to the clutch lever on the transmission. This often requires working in tight spaces.
Here's a comparison to put it in perspective:
Changing a clutch cable is typically less labor-intensive than a full clutch replacement but can be more fiddly than a standard brake service.
For context, a job like changing brakes on the front axle (replacing both
front brake discs and brake pads) is a very common and straightforward service. The
brake pads price for a set can range from $50 to $150 for decent quality parts, while the front brake discs can be $80 to $200 each. Therefore, the total
brakes cost for parts for a front axle service can be in the $200 to $500 range, plus 1-2 hours of labor.

A clutch cable replacement itself is an inexpensive part (usually $50-$150), but the labor is the main cost, typically taking 1-3 hours. So, while not the biggest job, it requires specific knowledge and can be time-consuming. It's highly recommended to have a professional handle it unless you have advanced DIY experience.