Talk that may have leaked out (3)
I believe the answer is:
gas
'talk' is the definition.
(gas can mean to chat)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for gas that I've seen before include "rabbit" , "Oxygen is one" , "Petrol (USA)" , "may fill American car" , "Petrol (US)" .)