The fifth or sixth letter in "knowledge" (4)
I believe the answer is:
lore
'knowledge' is the definition.
(lore is a kind of knowledge)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for lore that I've seen before include "Traditional belief" , "Ancient learning" , "old-fashioned thong" , "Folk knowledge" , "Role for tradition" .)