Delicious warm doughnut disappears (5)
I believe the answer is:
tasty
'delicious' is the definition.
(I've seen this in another clue)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for tasty that I've seen before include "Like nice grub" , "Mouth-watering" , "Delicious" , "Appetizing" , "Attractive, appealing" .)