Excessive amount weary of hit (8)
I believe the answer is:
overkill
'excessive amount' is the definition.
(I've seen this before)
'weary of hit' is the wordplay.
'weary of' becomes 'over' (I can't explain this - if you can you should believe this answer much more).
'hit' becomes 'kill' (I've seen this in another clue).
'over'+'kill'='OVERKILL'
Can you help me to learn more?
(Other definitions for overkill that I've seen before include "Excessive amount" , "much more than required" , "Excessive action, armament" , "Action far more drastic than necessary" , "Ridiculous excess" .)