Old 11+ expert employed after school foundation drops pupil.
Old 11 -> O ( mediaeval Roman for 11)
Expert -> ONER
School -> SCH
Definition: Foundation -> SCHOLARSHIP
drops pupil -> SCHOLARSHIP - SCHOLAR = SHIP
TYKE - though convoluted, thought it might appeal to English
crossword setters of a certain age, especially camouflaging the definition.
Others might care to differ, of course.