End of bout nothing to talk about (4)
I believe the answer is:
kayo
'end of bout' is the definition.
Although both the answer and definition are verbs in their base form, I can't see how they can define each other.
'nothing to talk about' is the wordplay.
'nothing' becomes 'o' (looks like zero - 0).
'to talk' becomes 'yak' (yak is a kind of talk**).
'about' shows that the letters should be reversed in order.
'o'+'yak'='oyak'
'oyak' back-to-front is 'KAYO'.
Can you help me to learn more?
(Other definitions for kayo that I've seen before include "Knockout" , "Conclusive end of a boxing match" , "Decisive blow (in boxing)" , "Decisive end to a fight?" , "KO (sl.)" .)