I believe the hard drive is failing and if you have any important data on it back it up immediately. Even though it passed you have some problems, especially due to the fact it is clicking. Is the clicking at constant intervals?
Current_Pending_Sector 0x0022 100 100 000 Old_age Always - 237
Pending Sectors are Sectors that cannot be read but are awaiting reallocation. Increases in this without an increase in the Reallocated Sector Count is bad.
Current Pending Sector Count
Count of "unstable" sectors (waiting to be remapped, because of unrecoverable read errors). If an unstable sector is subsequently read successfully, the sector is remapped and this value is decreased. Read errors on a sector will not remap the sector immediately (since the correct value cannot be read and so the value to remap is not known, and also it might become readable later); instead, the drive firmware remembers that the sector needs to be remapped, and will remap it the next time it's written. However some drives will not immediately remap such sectors when written; instead the drive will first attempt to write to the problem sector and if the write operation is successful then the sector will be marked good (in this case, the "Reallocation Event Count" (0xC4) will not be increased). This is a serious shortcoming, for if such a drive contains marginal sectors that consistently fail only after some time has passed following a successful write operation, then the drive will never remap these problem sectors.
ATA Error Count: 30866 (device log contains only the most recent five errors)
During the test you had 30866 errors and those were both Read and Write but the last five indicate mostly Write errors. Write errors being the worse of the two.
UNC means Uncorrectable but I yet to find what WP means, possibly Write Protect? I am not sure. Hopefully somebody else knows the answer.
If you do decide to keep the drive, I would not keep anything important on it. Before using it I would zero out the drive and reformat it.
Even though SMART says the test passed, SMART is not perfect. The test can pass and the drive still fail but after seeing your report I would err on the side of caution and replace the drive.