An elder can be full of knowledge (7)
I believe the answer is:
learned
'full of knowledge' is the definition.
(I've seen this before)
'an elder can be' is the wordplay.
'can be' indicates anagramming the letters.
'an'+'elder'='anelder'
'anelder' with letters rearranged gives 'LEARNED'.
(Other definitions for learned that I've seen before include "Picked up - well-read" , "Absorbed information about Leander" , "Got to know" , "Intellectual" , "Knowledgeable - scholarly" .)