Chap of knowledge? (3)
I believe the answer is:
ken
I believe this is a double definition.
'chap' is the first definition.
(man's name)
'knowledge?' is the second definition.
(ken is a kind of knowledge)
'of' acts as a link.
(Other definitions for ken that I've seen before include "Understanding - boy's name" , "Notice" , "Identify; -- Livingstone" , "Awareness" , "One's range of knowledge" .)