Charge (a liquid) with gas (6)
I believe the answer is:
aerate
'charge a liquid with gas' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for aerate that I've seen before include "Charge with carbon dioxide" , "Supply with oxygen" , "produce inflation?" , "Introduce gas to" , "Introduce air into" .)