Sweet, so-called character of Heidi? (5,4)
I believe the answer is:
swiss roll
'sweet' is the definition.
I cannot understand how the rest of the clue works.
(Other definitions for swiss roll that I've seen before include "Type of sponge cake" , "teatime treat?" , "Filled sponge cake" , "Cylindrical sponge cake with layers of jam" , "piece of cake?" .)