New role for knowledge (4)
I believe the answer is:
lore
'knowledge' is the definition.
(lore is a kind of knowledge)
'new role' is the wordplay.
'new' indicates anagramming the letters.
'role' anagrammed gives 'LORE'.
'for' is the link.
(Other definitions for lore that I've seen before include "Role for tradition" , "Old learning" , "Ancient learning" , "Role for body of traditions" , "old-fashioned thong" .)