"CLA" is a bit of jargon frequently seen in discussions of vintage cameras. It is an abbreviation for "clean, lube, and adjust."
Even if a camera is generally working, it may be worthwhile to have a competent technician give it a good overhaul—for example to clean viewfinders, calibrate shutter speeds, or to replace disintegrating foam rubber seals and bumpers. For many older cameras, original service parts may be unavailable; but in some cases these can be salvaged from a poor-condition "organ donor" camera of the same brand. It can be worth seeking out a repairer known for experience with a particular brand, as they'll be the most familiar with common problems and their solutions.
A occasional CLA can keep a good-quality camera in service over many, many decades.