Is the clear white fluid discharged after urination – following the retention of semen after masturbation – semen or madhiy, or does it become clear due to mixing with urine, and are ghusl and fasting permissible with it?

Masturbation is forbidden, and repentance from it is obligatory. Ghusl (ritual bath) is not required for one who holds back semen from exiting. Previous fatwas have clarified the signs that distinguish semen from pre-seminal fluid. If you are uncertain about which of them has exited, you may choose between the two. Purity (tahara) is not a condition for the validity of fasting.