Friend averages 50% tedious talk (7)
I believe the answer is:
palaver
'talk' is the definition.
(palavering is a kind of talking)
'friend averages' is the wordplay.
'friend' becomes 'pal' (pal can mean a friend).
'averages' becomes 'aver' (I can't explain this - if you can you should believe this answer much more).
'pal'+'aver'='PALAVER'
'50% tedious' acts as a link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for palaver that I've seen before include "Rigmarole" , "Fuss and bother" , "Rabbit" , "Idle copious talk" , "Confused talk and activity" .)