First-class addition to dessert, perhaps (7)
I believe the answer is:
topping
'first-class' is the definition.
(old-fashioned term meaning excellent)
'addition to dessert perhaps' is the wordplay.
I cannot really see how this works, but
'to' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for topping that I've seen before include "murder" , "Garnish - splendid!" , "Polishing off" , "Absolutely excellent!" , "garnish for food" .)