He may pass on what he knows (8)
I believe the answer is:
examinee
'he may pass on what he knows' is the definition.
The definition suggests a singular noun which matches the answer.
This is the entire clue.
Can you help me to learn more?
(Other definitions for examinee that I've seen before include "GCSE entrant" , "One's tested" , "in France, one taking the Baccalaureat?" , "Whipped dessert" , "One sitting a test" .)