Comment # 3 on bug 101594 from Jan Vesely

Blender uses whitelist of supported platform, clover is not a supported
platform.
if you run:
blender --debug-cycles
you should see message(s) like:
"Ignoring device ..., not officially supported yet"

running:
CYCLES_OPENCL_SPLIT_KERNEL_TEST=1 blender

will make clover devices visible to blender