A click is a discontinuity. Somewhere in the waveform, a handful of samples jump where the surrounding material is smooth, and the ear hears the jump rather than the samples. Removing one means finding the jump and putting plausible audio in its place.
Detection
The detector watches the second difference of the signal: how much the slope changes from sample to sample. Slow, smooth material sits near zero. An impulse spikes.
That figure is compared against a threshold derived from the recent material rather than a fixed number, so a quiet passage and a loud one are held to their own standards. The floor updates only on frames that were not flagged, which stops a run of clicks from raising the threshold that is supposed to catch them.
Repair
Once a click is found, the detector walks forward while the damage continues, up to the length cap. Then the damaged samples are replaced by a straight interpolation between the last good sample before and the first good sample after.
Over a few samples a straight line is indistinguishable from the waveform that should have been there. Over a few hundred it is silence with edges, which is why the length cap matters.
Lookahead
The repair needs to see the far side of a click before it can draw across it, so the step holds 12 ms of audio and reports that as its latency. The preview delays its comparison path by the same amount, and the export strips it from the front of the file.
Sensitivity
Low values catch only the obvious damage and leave transients alone. High values catch quiet ticks and start treating drum hits as faults.
Work from below. Raise it until the clicks stop, listen to the loudest transient in the file, and stop before it dulls.
Order in a chain
First, before the denoiser and before any EQ. A click is broadband, so a noise estimate built while clicks are still present carries a little of every click in it, and filtering spreads each click into a longer smear that is harder to detect afterward.