It seems at least some of the disk image handling utilities are capable of performing conversion between CloneCD disk images (.img) and Unix tape archives (.tar). Should be standard disk image conversion, typically used to transfer data to a format supported on Linux.
Convert CloneCD image file to Unix standard Archive format, Tape Archive.
We have found one software suitable in our database for this conversion.
Apple macOS / Mac OS X software - convert img to tar on OS X
A dedicated utility for DMG format, DropDMG is the easiest way to create Mac OS X disk images. Just drag and drop a folder or file, and DropDMG will create an image in .dmg, .img, or .smi format—or a Tar, Zip, or StuffIt archive.
Convert from img file
to tar file
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.