Ingredient for baking best doughnut substantially covers pastry (5,2,6)
I believe the answer is:
cream of tartar
'ingredient for baking' is the definition.
I can't judge whether this defines the answer.
'best doughnut substantially covers pastry' is the wordplay.
'best' becomes 'cream' (both can mean the elite).
'doughnut' becomes 'o' (letter resembling a doughnut).
'substantially' becomes 'far' (I've seen this in another clue).
'covers' indicates putting letters inside.
'pastry' becomes 'tart' (type of pastry).
'far' placed around 'tart' is 'ftartar'.
'cream'+'o'+'ftartar'='CREAM OF TARTAR'
Can you help me to learn more?
(Other definitions for cream of tartar that I've seen before include "Cooking ingredient" , "White powder used in baking" , "Substance used in baking powder" , "cake baked with this?" , "An ingredient of baking powder" .)