Sweet thing in cakes is needed, getting topping on those? (5)
I believe the answer is:
icing
'sweet thing' is the definition.
(I've seen this before)
'in cakes is needed getting topping on those?' is the wordplay.
I cannot really see how this works, but
'in' is within 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 icing that I've seen before include "effect of cold weather" , "white coat" , "in the freezer?" , "Sugar coating as cake decoration" , "Possibly the nicest part of the cake" .)