American Tyson finally knocked out jabber (3)
I believe the answer is:
yak
'jabber' is the definition.
(I've seen this in another clue)
'american tyson finally knocked out' is the wordplay.
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'tyson finally' becomes 'ky' (I can't explain this - if you can you should believe this answer much more).
'knocked' is a reversal indicator (I've seen 'knocking' mean this).
'out' indicates putting letters inside.
'ky' back-to-front is 'yk'.
'a' inserted inside 'yk' is 'YAK'.
Can you help me to learn more?
(Other definitions for yak that I've seen before include "Rabbit on" , "one sporting a thick coat" , "Shaggy-haired ox" , "Gossip; ox" , "A long-haired Asian ox" .)