Writing bound to be a feat of athleticism (10)
I believe the answer is:
handspring
'a feat of athleticism' is the definition.
'writing bound' is the wordplay.
'writing' becomes 'hand' (hand is a kind of writing).
'bound' becomes 'spring' ('spring' can be a synonym of 'bound'**).
'hand'+'spring'='HANDSPRING'
'to be' is the link.
(Other definitions for handspring that I've seen before include "Jump using hands" , "Gymnast may perform this" , "turnover" , "Somersault, cartwheel" , "gymnastic feat" .)