Answered by Ustadha Shazia Ahmad
After ejaculation, the person urinates and then takes ghusl. After the ghusl he notices a clear sticky fluid on his underwear (appears to be prostate fluid), does he have to make another ghusl as this fluid always accompanies sexual arousal but is distinct from the semen as mentioned in the books of fiqh?
The following link describes how to identify semen. If the liquid meets the criterion of semen, a ghusl would be required, otherwise not. Note that it is common for semen to exit a while after ejaculation if one has since urinated.
Post-Ghusl Exiting of Ejaculate (maniyy)
And Allah knows best.