Apple never licensed OS X to clone makers. The clone era was very short (at most 1993-1997), and ended while the Classic MacOS was current. OS X didn't ship until 2001.
Apple licensed variants of OS 7 to the clone makers. When Steve returned, someone decided that the clone license agreements did not cover OS 8 ... so boom. New OS, but no new license. IIRC, Apple did buy one of the clone makers (possibly Power Computing).
