Make effervescent, put air into (6)
I believe the answer is:
aerate
This clue is a double definition.
'make effervescent' is the first definition.
(I've seen this in another clue)
'put air into' is the second definition.
(I've seen this before)
(Other definitions for aerate that I've seen before include "get excited" , "Fill with bubbly gas" , "Charge with a gas" , "Fill with oxygen" , "Add carbon dioxide to liquid - make bubbly" .)