Staff reaching a point with 50% of children going back into some form of education (4)
I believe the answer is:
pike
'staff reaching a point' is the definition.
I cannot understand how the remainder of the clue works.
(Other definitions for pike that I've seen before include "jackknife" , "Fish - medieval weapon" , "Fresh-water fish or old spear" , "Long European freshwater predator" , "Predatory freshwater fish" .)