Retain knowledge about one of the team (8)
I believe the answer is:
remember
'retain knowledge' is the definition.
'remember' can be an answer for 'retain' (thesaurus). I am not certain of the 'knowledge' bit.
'about one of the team' is the wordplay.
'about' becomes 're' ('re' means regarding or about).
'one of the team' becomes 'member' (I can't justify this - if you can you should believe this answer much more).
're'+'member'='REMEMBER'
Can you help me to learn more?
(Other definitions for remember that I've seen before include "Be sure" , "Recall to mind" , "Commemorate" , "Mark" , "Think back" .)