Almost making a mess of cake (6)
I believe the answer is:
muffin
'cake' is the definition.
(I've seen this before)
I don't understand the rest of the clue.
(Other definitions for muffin that I've seen before include "Round raised cake, often split and toasted" , "Tea cake" , "Cake - old TV mule" , "Toasted, spongy bread roll" , "Small cake" .)