Batch of trainees at the point of arrival (6)
I believe the answer is:
intake
'batch' is the definition.
(I have seen 'batch of students' mean 'intake' so perhaps 'batch' could also mean 'intake')
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for intake that I've seen before include "Consumption" , "Number of acceptances as in school" , "Body of new pupils" , "Fresh pupils" , "(Quantity of) new students accepted by school" .)