Stomachache reliever, familiarly (6)
I believe the answer is:
bicarb
'stomachache reliever familiarly' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for bicarb that I've seen before include "What helps raise" , "Baking compound" , "Raising agent in baking (colloq.)" , "Digestive remedy (abbr)" , "Baking soda (abbr)" .)