Sporting, and newly prepared for defeat (10)
I believe the answer is:
frolicking
'sporting' is the definition.
('frolic' can be a synonym of 'sport')
'newly prepared for defeat' is the wordplay.
'newly prepared' indicates anagramming the letters.
'defeat' becomes 'licking' (licking is a kind of defeat).
'for' with letters rearranged gives 'fro'.
'fro'+'licking'='FROLICKING'
'and' acts as a link.
(Other definitions for frolicking that I've seen before include "Gambolling about" , "light-hearted playing" , "Indulging in playful behaviour" , "Having fun" .)