Caper is a risk, we hear (6)
I believe the answer is:
gambol
'caper' is the definition.
(I know that caper can be written as gambol)
'risk we hear' is the wordplay.
'risk' becomes 'gamble' (gamble is a kind of risk).
'we hear' indicates a 'sounds like' (homophone) clue.
'gamble' is a homophone of 'GAMBOL'.
'is a' acts as a link.
(Other definitions for gambol that I've seen before include "Prance; sounds like bet" , "Playfully run or jump" , "Caper and cavort (6)" , "Skip" , "Frisk and play" .)