Irritability is good for your digestion! (4)
I believe the answer is:
bile
This clue might be a double definition.
'irritability' is the first definition.
(I've seen this in another clue)
'good for your digestion' is the second definition.
I know that 'digestion' relates to this answer.
'is' is the link.
Can you help me to learn more?
(Other definitions for bile that I've seen before include "Bitterness - digestive fluid stored in the gall bladder" , "Peevish temper; a liver secretion" , "Fluid secreted by the liver" , "Anger, bitterness" , "Digestive juice secreted by the liver" .)