Petition heard in quarry (4)
I believe the answer is:
prey
'quarry' is the definition.
(I know that quarry can be written as prey)
'petition heard' is the wordplay.
'petition' becomes 'pray' (I've seen this before).
'heard' indicates a 'sounds like' (homophone) clue.
'pray' is a homophone of 'PREY'.
'in' is the link.
(Other definitions for prey that I've seen before include "Animal sought as food" , "Quarry, fair game" , "Quarry, target" , "Animal hunted and killed for food" , "Animal's quarry" .)