If one becomes clean from menstruation after sahur. Can she continue with her fast?
Unfortunately, no. Finishing one’s period after Sahur (after Adhān of Fajr prayers) doesn’t entitle one, for fasting for that day. This is because, fasting must take place with intention and (optional Sahūr) before the Adhān of Fajr prayers.
This is also, unlike the one who finishes her menstruation before dawn time (Saḥūr/Fajr). She can make her intention and fast, and prepare for ṣalāh (prayers) before or after Adhān.
Allāh knows best.