When speaking, beg for quarry (4)
I believe the answer is:
prey
'quarry' is the definition.
(I know that quarry can be written as prey)
'when speaking beg' is the wordplay.
'when speaking' shows a homophone (sound like).
'beg' becomes 'pray' (synonyms).
'pray' is a homophone of 'PREY'.
'for' is the link.
(Other definitions for prey that I've seen before include "Hunted creature" , "Animal hunted by another for food" , "Animal hunted or caught for food" , "Victim, quarry" , "Animal's victim" .)