Its all very logical. If the clue says head of garlic, then it means the letter 'g' is in the answer. I could just as well have said 'head of grouse' or head of 'goose'. Its only the 'g' you use so ignore the rest of the letters in 'garlic'. So you are then looking for 5 more letters to make a word meaning ' a stew'. So what are we left with?So I'm guess stew is the word indicating the anagram? But where did that leave me for the rest. Head indicates to take the first letter of which word because the is no 5 lettered word in that clue... Guessing that I take the letter g from garlic butdoes that leave me with the letter g or 5 letters arlic that I need to add another letter to?
Foolishly (that indicates an anagram) eat (head of garlic = g) in, a stew (stew indicates the meaning of the solution).