What is the ruling on the clear fluid that is discharged upon feeling aroused, and does ghusl become obligatory if something is discharged when a girl crosses her legs, without intending masturbation, and is her action considered masturbation?

Pre-seminal fluid (madhiy) necessitates ablution (wudu') and cleansing whatever it has touched on the body and clothes. Seminal fluid (maniy) necessitates a ritual bath (ghusl). What the questioner mentioned is not among the prohibited acts of masturbation, and there is no sin upon her for it.