This is not at all saying the clinic is closing. It is saying they are closing the waiting list for new referrals.
They have struggled in recent years to recruit staff and this looks like a staffing problem. If they manage to recruit staff, they will reopen the waiting list.
In the meantime, they are busy shunting the 17 year olds on the waiting lists to the adult clinics where their time on the Sandyford lists are counted as “time served”, resulting in some 17 year olds receiving immediate appointments at the adult clinics.