Simmer (4)
'simmer' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for stew that I've seen before include "West (anag.)" , "are nervous" , "anxious state" , "Slow cooked meat dish" , "Wet food for wets" .)
(Other definitions for boil that I've seen before include "Bubble up - inflamed swelling" , "Cook in hot water" , "Skin swelling; cause to evaporate" , "become inflamed" , "7 in water" .)